From 014c988e319d1e17b7992b591b08d2fefab18de1 Mon Sep 17 00:00:00 2001
From: ElliottKasoar <45317199+ElliottKasoar@users.noreply.github.com>
Date: Fri, 8 Nov 2024 10:44:29 +0000
Subject: [PATCH] Update docstrings (#348)

---
 janus_core/calculations/base.py         |  46 +++++-----
 janus_core/calculations/descriptors.py  |  36 ++++----
 janus_core/calculations/eos.py          |  48 +++++-----
 janus_core/calculations/geom_opt.py     |  56 ++++++------
 janus_core/calculations/md.py           | 116 ++++++++++++------------
 janus_core/calculations/phonons.py      |  88 +++++++++---------
 janus_core/calculations/single_point.py |  34 +++----
 janus_core/helpers/log.py               |  14 +--
 janus_core/helpers/mlip_calculators.py  |   8 +-
 janus_core/helpers/struct_io.py         |  22 ++---
 janus_core/helpers/utils.py             |   6 +-
 janus_core/processing/post_process.py   |  14 +--
 janus_core/training/train.py            |   6 +-
 tests/utils.py                          |   2 +-
 14 files changed, 248 insertions(+), 248 deletions(-)

diff --git a/janus_core/calculations/base.py b/janus_core/calculations/base.py
index 7146ac5e..0797b1db 100644
--- a/janus_core/calculations/base.py
+++ b/janus_core/calculations/base.py
@@ -26,46 +26,46 @@ class BaseCalculation(FileNameMixin):
     ----------
     calc_name : str
         Name of calculation being run, used for name of logger. Default is "base".
-    struct : Optional[MaybeSequence[Atoms]]
+    struct : MaybeSequence[Atoms] | None
         ASE Atoms structure(s) to simulate. Required if `struct_path` is None.
         Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to simulate. Required if `struct` is None.
         Default is None.
     arch : Architectures
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
     read_kwargs : ASEReadArgs
         Keyword arguments to pass to ase.io.read. Default is {}.
     sequence_allowed : bool
         Whether a sequence of Atoms objects is allowed. Default is True.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is None.
-    additional_prefix : Optional[str]
+    additional_prefix : str | None
         Component to add to default file_prefix (joined by hyphens). Default is None.
-    param_prefix : Optional[str]
+    param_prefix : str | None
         Additional parameters to add to default file_prefix. Default is None.
 
     Attributes
     ----------
-    logger : Optional[logging.Logger]
+    logger : logging.Logger | None
         Logger if log file has been specified.
-    tracker : Optional[OfflineEmissionsTracker]
+    tracker : OfflineEmissionsTracker | None
         Tracker if logging is enabled.
     """
 
@@ -97,40 +97,40 @@ def __init__(
         ----------
         calc_name : str
             Name of calculation being run, used for name of logger. Default is "base".
-        struct : Optional[MaybeSequence[Atoms]]
+        struct : MaybeSequence[Atoms] | None
             ASE Atoms structure(s) to simulate. Required if `struct_path` is None.
             Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to simulate. Required if `struct` is None. Default is
             None.
         arch : Architectures
             MLIP architecture to use for calculations. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. Default is {}.
         sequence_allowed : bool
             Whether a sequence of Atoms objects is allowed. Default is True.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is None.
-        additional_prefix : Optional[str]
+        additional_prefix : str | None
             Component to add to default file_prefix (joined by hyphens). Default is
             None.
-        param_prefix : Optional[str]
+        param_prefix : str | None
             Additional parameters to add to default file_prefix. Default is None.
         """
         (read_kwargs, calc_kwargs, log_kwargs, tracker_kwargs) = none_to_dict(
diff --git a/janus_core/calculations/descriptors.py b/janus_core/calculations/descriptors.py
index 95425d15..f8fa98ad 100644
--- a/janus_core/calculations/descriptors.py
+++ b/janus_core/calculations/descriptors.py
@@ -28,32 +28,32 @@ class Descriptors(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[MaybeSequence[Atoms]]
+    struct : MaybeSequence[Atoms] | None
         ASE Atoms structure(s) to calculate descriptors for. Required if `struct_path`
         is None. Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to calculate descriptors for. Required if `struct` is None.
         Default is None.
     arch : Architectures
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run MLIP model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    read_kwargs : Optional[ASEReadArgs]
+    read_kwargs : ASEReadArgs | None
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is -1.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
     invariants_only : bool
         Whether only the invariant descriptors should be returned. Default is True.
@@ -63,7 +63,7 @@ class Descriptors(BaseCalculation):
         Whether to calculate descriptors for each atom. Default is False.
     write_results : bool
         True to write out structure with results of calculations. Default is False.
-    write_kwargs : Optional[ASEWriteArgs],
+    write_kwargs : ASEWriteArgs | None
         Keyword arguments to pass to ase.io.write if saving structure with
         results of calculations. Default is {}.
 
@@ -98,32 +98,32 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[MaybeSequence[Atoms]]
+        struct : MaybeSequence[Atoms] | None
             ASE Atoms structure(s) to calculate descriptors for. Required if
             `struct_path` is None. Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to calculate descriptors for. Required if `struct` is
             None. Default is None.
         arch : Architectures
             MLIP architecture to use for calculations. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is -1.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
         invariants_only : bool
             Whether only the invariant descriptors should be returned. Default is True.
@@ -133,7 +133,7 @@ def __init__(
             Whether to calculate descriptors for each atom. Default is False.
         write_results : bool
             True to write out structure with results of calculations. Default is False.
-        write_kwargs : Optional[ASEWriteArgs],
+        write_kwargs : ASEWriteArgs | None
             Keyword arguments to pass to ase.io.write if saving structure with
             results of calculations. Default is {}.
         """
diff --git a/janus_core/calculations/eos.py b/janus_core/calculations/eos.py
index 1ddd3ee7..09926588 100644
--- a/janus_core/calculations/eos.py
+++ b/janus_core/calculations/eos.py
@@ -31,32 +31,32 @@ class EoS(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[Atoms]
+    struct : Atoms | None
         ASE Atoms structure to calculate equation of state for. Required if
         `struct_path` is None. Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to calculate equation of state for. Required if `struct` is
         None. Default is None.
     arch : Architectures
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run MLIP model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    read_kwargs : Optional[ASEReadArgs]
+    read_kwargs : ASEReadArgs | None
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is -1.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
     min_volume : float
         Minimum volume scale factor. Default is 0.95.
@@ -70,20 +70,20 @@ class EoS(BaseCalculation):
         Whether to minimize initial structure before calculations. Default is True.
     minimize_all : bool
         Whether to optimize geometry for all generated structures. Default is False.
-    minimize_kwargs : Optional[dict[str, Any]]
+    minimize_kwargs : dict[str, Any] | None
         Keyword arguments to pass to optimize. Default is None.
     write_results : bool
         True to write out results of equation of state calculations. Default is True.
     write_structures : bool
         True to write out all genereated structures. Default is False.
-    write_kwargs : Optional[OutputKwargs],
+    write_kwargs : OutputKwargs | None
         Keyword arguments to pass to ase.io.write to save generated structures.
         Default is {}.
     plot_to_file : bool
         Whether to save plot equation of state to svg. Default is False.
-    plot_kwargs : Optional[dict[str, Any]]
+    plot_kwargs : dict[str, Any] | None
         Keyword arguments to pass to EquationOfState.plot. Default is {}.
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is inferred from structure name, or
         chemical formula of the structure.
 
@@ -138,32 +138,32 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[Atoms]
+        struct : Atoms | None
             ASE Atoms structure to optimize geometry for. Required if `struct_path` is
             None. Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to optimize. Required if `struct` is None. Default is
             None.
         arch : Architectures
             MLIP architecture to use for optimization. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is -1.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
         min_volume : float
             Minimum volume scale factor. Default is 0.95.
@@ -178,21 +178,21 @@ def __init__(
         minimize_all : bool
             Whether to optimize geometry for all generated structures. Default is
             False.
-        minimize_kwargs : Optional[dict[str, Any]]
+        minimize_kwargs : dict[str, Any] | None
             Keyword arguments to pass to optimize. Default is None.
         write_results : bool
             True to write out results of equation of state calculations. Default is
             True.
         write_structures : bool
             True to write out all genereated structures. Default is False.
-        write_kwargs : Optional[OutputKwargs],
+        write_kwargs : OutputKwargs | None
             Keyword arguments to pass to ase.io.write to save generated structures.
             Default is {}.
         plot_to_file : bool
             Whether to save plot equation of state to svg. Default is False.
-        plot_kwargs : Optional[dict[str, Any]]
+        plot_kwargs : dict[str, Any] | None
             Keyword arguments to pass to EquationOfState.plot. Default is {}.
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is inferred from structure name, or
             chemical formula of the structure.
         """
diff --git a/janus_core/calculations/geom_opt.py b/janus_core/calculations/geom_opt.py
index 3f4c155e..170ae3f8 100644
--- a/janus_core/calculations/geom_opt.py
+++ b/janus_core/calculations/geom_opt.py
@@ -32,31 +32,31 @@ class GeomOpt(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[Atoms]
+    struct : Atoms | None
         ASE Atoms structure to optimize geometry for. Required if `struct_path` is
         None. Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to optimize. Required if `struct` is None. Default is None.
     arch : Architectures
         MLIP architecture to use for optimization. Default is "mace_mp".
     device : Devices
         Device to run MLIP model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    read_kwargs : Optional[ASEReadArgs]
+    read_kwargs : ASEReadArgs | None
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is -1.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
     fmax : float
         Set force convergence criteria for optimizer in units eV/Å. Default is 0.1.
@@ -70,22 +70,22 @@ class GeomOpt(BaseCalculation):
     angle_tolerance : float
         Angle precision for spglib symmetry determination, in degrees. Default is -1.0,
         which means an internally optimized routine is used to judge symmetry.
-    filter_func : Optional[Union[Callable, str]]
+    filter_func : Callable | str | None
         Filter function, or name of function from ase.filters to apply constraints to
         atoms. Default is `FrechetCellFilter`.
-    filter_kwargs : Optional[dict[str, Any]]
+    filter_kwargs : dict[str, Any] | None
         Keyword arguments to pass to filter_func. Default is {}.
-    optimizer : Union[Callable, str]
+    optimizer : Callable | str
         Optimization function, or name of function from ase.optimize. Default is
         `LBFGS`.
-    opt_kwargs : Optional[ASEOptArgs]
+    opt_kwargs : ASEOptArgs | None
         Keyword arguments to pass to optimizer. Default is {}.
     write_results : bool
         True to write out optimized structure. Default is False.
-    write_kwargs : Optional[OutputKwargs],
+    write_kwargs : OutputKwargs | None
         Keyword arguments to pass to ase.io.write to save optimized structure.
         Default is {}.
-    traj_kwargs : Optional[OutputKwargs]
+    traj_kwargs : OutputKwargs | None
         Keyword arguments to pass to ase.io.write to save optimization trajectory.
         Must include "filename" keyword. Default is {}.
 
@@ -129,32 +129,32 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[Atoms]
+        struct : Atoms | None
             ASE Atoms structure to optimize geometry for. Required if `struct_path` is
             None. Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to optimize. Required if `struct` is None. Default is
             None.
         arch : Architectures
             MLIP architecture to use for optimization. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is -1.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
         fmax : float
             Set force convergence criteria for optimizer in units eV/Å. Default is 0.1.
@@ -168,22 +168,22 @@ def __init__(
         angle_tolerance : float
             Angle precision for spglib symmetry determination, in degrees. Default is
             -1.0, which means an internally optimized routine is used to judge symmetry.
-        filter_func : Optional[Union[Callable, str]]
+        filter_func : Callable | str | None
             Filter function, or name of function from ase.filters to apply constraints
             to atoms. Default is `FrechetCellFilter`.
-        filter_kwargs : Optional[dict[str, Any]]
+        filter_kwargs : dict[str, Any] | None
             Keyword arguments to pass to filter_func. Default is {}.
-        optimizer : Union[Callable, str]
+        optimizer : Callable | str
             Optimization function, or name of function from ase.optimize. Default is
             `LBFGS`.
-        opt_kwargs : Optional[ASEOptArgs]
+        opt_kwargs : ASEOptArgs | None
             Keyword arguments to pass to optimizer. Default is {}.
         write_results : bool
             True to write out optimized structure. Default is False.
-        write_kwargs : Optional[OutputKwargs],
+        write_kwargs : OutputKwargs | None
             Keyword arguments to pass to ase.io.write to save optimized structure.
             Default is {}.
-        traj_kwargs : Optional[OutputKwargs]
+        traj_kwargs : OutputKwargs | None
             Keyword arguments to pass to ase.io.write to save optimization trajectory.
             Must include "filename" keyword. Default is {}.
         """
diff --git a/janus_core/calculations/md.py b/janus_core/calculations/md.py
index 4f17d883..3b691795 100644
--- a/janus_core/calculations/md.py
+++ b/janus_core/calculations/md.py
@@ -52,31 +52,31 @@ class MolecularDynamics(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[Atoms]
+    struct : Atoms | None
         ASE Atoms structure to simulate. Required if `struct_path` is None. Default is
         None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to simulate. Required if `struct` is None. Default is None.
     arch : Architectures
         MLIP architecture to use for simulation. Default is "mace_mp".
     device : Devices
         Device to run MLIP model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    read_kwargs : Optional[ASEReadArgs]
+    read_kwargs : ASEReadArgs | None
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is -1.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
     struct : Atoms
         Structure to simulate.
@@ -96,7 +96,7 @@ class MolecularDynamics(BaseCalculation):
     minimize_every : int
         Frequency of minimizations. Default is -1, which disables minimization after
         beginning dynamics.
-    minimize_kwargs : Optional[dict[str, Any]]
+    minimize_kwargs : dict[str, Any] | None
         Keyword arguments to pass to geometry optimizer. Default is {}.
     rescale_velocities : bool
         Whether to rescale velocities. Default is False.
@@ -104,7 +104,7 @@ class MolecularDynamics(BaseCalculation):
         Whether to remove rotation. Default is False.
     rescale_every : int
         Frequency to rescale velocities. Default is 10.
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is inferred from structure, ensemble,
         and temperature.
     restart : bool
@@ -119,14 +119,14 @@ class MolecularDynamics(BaseCalculation):
         Whether to rotate restart files. Default is False.
     restarts_to_keep : int
         Restart files to keep if rotating. Default is 4.
-    final_file : Optional[PathLike]
+    final_file : PathLike | None
         File to save final configuration at each temperature of similation. Default
         inferred from `file_prefix`.
-    stats_file : Optional[PathLike]
+    stats_file : PathLike | None
         File to save thermodynamical statistics. Default inferred from `file_prefix`.
     stats_every : int
         Frequency to output statistics. Default is 100.
-    traj_file : Optional[PathLike]
+    traj_file : PathLike | None
         Trajectory file to save. Default inferred from `file_prefix`.
     traj_append : bool
         Whether to append trajectory. Default is False.
@@ -134,23 +134,23 @@ class MolecularDynamics(BaseCalculation):
         Step to start saving trajectory. Default is 0.
     traj_every : int
         Frequency of steps to save trajectory. Default is 100.
-    temp_start : Optional[float]
+    temp_start : float | None
         Temperature to start heating, in K. Default is None, which disables heating.
-    temp_end : Optional[float]
+    temp_end : float | None
         Maximum temperature for heating, in K. Default is None, which disables heating.
-    temp_step : Optional[float]
+    temp_step : float | None
         Size of temperature steps when heating, in K. Default is None, which disables
         heating.
-    temp_time : Optional[float]
+    temp_time : float | None
         Time between heating steps, in fs. Default is None, which disables heating.
-    write_kwargs : Optional[OutputKwargs],
+    write_kwargs : OutputKwargs | None
         Keyword arguments to pass to `output_structs` when saving trajectory and final
         files. Default is {}.
-    post_process_kwargs : Optional[PostProcessKwargs]
+    post_process_kwargs : PostProcessKwargs | None
         Keyword arguments to control post-processing operations.
-    correlation_kwargs : Optional[CorrelationKwargs]
+    correlation_kwargs : CorrelationKwargs | None
         Keyword arguments to control on-the-fly correlations.
-    seed : Optional[int]
+    seed : int | None
         Random seed used by numpy.random and random functions, such as in Langevin.
         Default is None.
 
@@ -228,32 +228,32 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[Atoms]
+        struct : Atoms | None
             ASE Atoms structure to simulate. Required if `struct_path` is None. Default
             is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to simulate. Required if `struct` is None. Default is
             None.
         arch : Architectures
             MLIP architecture to use for simulation. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is -1.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is None.
@@ -271,7 +271,7 @@ def __init__(
         minimize_every : int
             Frequency of minimizations. Default is -1, which disables minimization
             after beginning dynamics.
-        minimize_kwargs : Optional[dict[str, Any]]
+        minimize_kwargs : dict[str, Any] | None
             Keyword arguments to pass to geometry optimizer. Default is {}.
         rescale_velocities : bool
             Whether to rescale velocities. Default is False.
@@ -279,7 +279,7 @@ def __init__(
             Whether to remove rotation. Default is False.
         rescale_every : int
             Frequency to rescale velocities. Default is 10.
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is inferred from structure, ensemble,
             and temperature.
         restart : bool
@@ -294,15 +294,15 @@ def __init__(
             Whether to rotate restart files. Default is False.
         restarts_to_keep : int
             Restart files to keep if rotating. Default is 4.
-        final_file : Optional[PathLike]
+        final_file : PathLike | None
             File to save final configuration at each temperature of similation. Default
             inferred from `file_prefix`.
-        stats_file : Optional[PathLike]
+        stats_file : PathLike | None
             File to save thermodynamical statistics. Default inferred from
             `file_prefix`.
         stats_every : int
             Frequency to output statistics. Default is 100.
-        traj_file : Optional[PathLike]
+        traj_file : PathLike | None
             Trajectory file to save. Default inferred from `file_prefix`.
         traj_append : bool
             Whether to append trajectory. Default is False.
@@ -310,25 +310,25 @@ def __init__(
             Step to start saving trajectory. Default is 0.
         traj_every : int
             Frequency of steps to save trajectory. Default is 100.
-        temp_start : Optional[float]
+        temp_start : float | None
             Temperature to start heating, in K. Default is None, which disables
             heating.
-        temp_end : Optional[float]
+        temp_end : float | None
             Maximum temperature for heating, in K. Default is None, which disables
             heating.
-        temp_step : Optional[float]
+        temp_step : float | None
             Size of temperature steps when heating, in K. Default is None, which
             disables heating.
-        temp_time : Optional[float]
+        temp_time : float | None
             Time between heating steps, in fs. Default is None, which disables heating.
-        write_kwargs : Optional[OutputKwargs],
+        write_kwargs : OutputKwargs | None
             Keyword arguments to pass to `output_structs` when saving trajectory and
             final files. Default is {}.
-        post_process_kwargs : Optional[PostProcessKwargs]
+        post_process_kwargs : PostProcessKwargs | None
             Keyword arguments to control post-processing operations.
-        correlation_kwargs : Optional[list[CorrelationKwargs]]
+        correlation_kwargs : list[CorrelationKwargs] | None
             Keyword arguments to control on-the-fly correlations.
-        seed : Optional[int]
+        seed : int | None
             Random seed used by numpy.random and random functions, such as in Langevin.
             Default is None.
         """
@@ -641,7 +641,7 @@ def _set_param_prefix(self, file_prefix: PathLike | None = None) -> str:
 
         Parameters
         ----------
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames on class init. If not None, param_prefix = "".
 
         Returns
@@ -1136,10 +1136,10 @@ class NPT(MolecularDynamics):
         Pressure, in GPa. Default is 0.0.
     ensemble : Ensembles
         Name for thermodynamic ensemble. Default is "npt".
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is inferred from structure, ensemble,
         temperature, and pressure.
-    ensemble_kwargs : Optional[dict[str, Any]]
+    ensemble_kwargs : dict[str, Any] | None
         Keyword arguments to pass to ensemble initialization. Default is {}.
     **kwargs
         Additional keyword arguments.
@@ -1179,10 +1179,10 @@ def __init__(
             Pressure, in GPa. Default is 0.0.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is "npt".
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is inferred from structure, ensemble,
             temperature, and pressure.
-        ensemble_kwargs : Optional[dict[str, Any]]
+        ensemble_kwargs : dict[str, Any] | None
             Keyword arguments to pass to ensemble initialization. Default is {}.
         **kwargs
             Additional keyword arguments.
@@ -1219,7 +1219,7 @@ def _set_param_prefix(self, file_prefix: PathLike | None = None) -> str:
 
         Parameters
         ----------
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames on class init. If not None, param_prefix = "".
 
         Returns
@@ -1283,7 +1283,7 @@ class NVT(MolecularDynamics):
         Friction coefficient in fs^-1. Default is 0.005.
     ensemble : Ensembles
         Name for thermodynamic ensemble. Default is "nvt".
-    ensemble_kwargs : Optional[dict[str, Any]]
+    ensemble_kwargs : dict[str, Any] | None
         Keyword arguments to pass to ensemble initialization. Default is {}.
     **kwargs
         Additional keyword arguments.
@@ -1313,7 +1313,7 @@ def __init__(
             Friction coefficient in fs^-1. Default is 0.005.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is "nvt".
-        ensemble_kwargs : Optional[dict[str, Any]]
+        ensemble_kwargs : dict[str, Any] | None
             Keyword arguments to pass to ensemble initialization. Default is {}.
         **kwargs
             Additional keyword arguments.
@@ -1378,7 +1378,7 @@ class NVE(MolecularDynamics):
         Additional arguments.
     ensemble : Ensembles
         Name for thermodynamic ensemble. Default is "nve".
-    ensemble_kwargs : Optional[dict[str, Any]]
+    ensemble_kwargs : dict[str, Any] | None
         Keyword arguments to pass to ensemble initialization. Default is {}.
     **kwargs
         Additional keyword arguments.
@@ -1405,7 +1405,7 @@ def __init__(
             Additional arguments.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is "nve".
-        ensemble_kwargs : Optional[dict[str, Any]]
+        ensemble_kwargs : dict[str, Any] | None
             Keyword arguments to pass to ensemble initialization. Default is {}.
         **kwargs
             Additional keyword arguments.
@@ -1433,7 +1433,7 @@ class NVT_NH(NPT):  # noqa: N801 (invalid-class-name)
         Thermostat time, in fs. Default is 50.0.
     ensemble : Ensembles
         Name for thermodynamic ensemble. Default is "nvt-nh".
-    ensemble_kwargs : Optional[dict[str, Any]]
+    ensemble_kwargs : dict[str, Any] | None
         Keyword arguments to pass to ensemble initialization. Default is {}.
     **kwargs
         Additional keyword arguments.
@@ -1458,7 +1458,7 @@ def __init__(
             Thermostat time, in fs. Default is 50.0.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is "nvt-nh".
-        ensemble_kwargs : Optional[dict[str, Any]]
+        ensemble_kwargs : dict[str, Any] | None
             Keyword arguments to pass to ensemble initialization. Default is {}.
         **kwargs
             Additional keyword arguments.
@@ -1527,10 +1527,10 @@ class NPH(NPT):
         Pressure, in GPa. Default is 0.0.
     ensemble : Ensembles
         Name for thermodynamic ensemble. Default is "nph".
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is inferred from structure, ensemble,
         temperature, and pressure.
-    ensemble_kwargs : Optional[dict[str, Any]]
+    ensemble_kwargs : dict[str, Any] | None
         Keyword arguments to pass to ensemble initialization. Default is {}.
     **kwargs
         Additional keyword arguments.
@@ -1567,10 +1567,10 @@ def __init__(
             Pressure, in GPa. Default is 0.0.
         ensemble : Ensembles
             Name for thermodynamic ensemble. Default is "nph".
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is inferred from structure, ensemble,
             temperature, and pressure.
-        ensemble_kwargs : Optional[dict[str, Any]]
+        ensemble_kwargs : dict[str, Any] | None
             Keyword arguments to pass to ensemble initialization. Default is {}.
         **kwargs
             Additional keyword arguments.
diff --git a/janus_core/calculations/phonons.py b/janus_core/calculations/phonons.py
index ffc3cfc5..b69c5ed6 100644
--- a/janus_core/calculations/phonons.py
+++ b/janus_core/calculations/phonons.py
@@ -31,34 +31,34 @@ class Phonons(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[Atoms]
+    struct : Atoms | None
         ASE Atoms structure to calculate phonons for. Required if `struct_path` is
         None. Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to calculate phonons for. Required if `struct` is None.
         Default is None.
     arch : Architectures
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run MLIP model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    read_kwargs : Optional[ASEReadArgs]
+    read_kwargs : ASEReadArgs | None
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is -1.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
-    calcs : Optional[MaybeSequence[PhononCalcs]]
+    calcs : MaybeSequence[PhononCalcs] | None
         Phonon calculations to run. Default calculates force constants only.
     supercell : MaybeList[int]
         The size of a supercell for calculation, or the supercell itself.
@@ -79,7 +79,7 @@ class Phonons(BaseCalculation):
     minimize : bool
         Whether to perform geometry optimisation before calculating phonons.
         Default is False.
-    minimize_kwargs : Optional[dict[str, Any]]
+    minimize_kwargs : dict[str, Any] | None
         Keyword arguments to pass to geometry optimizer. Default is {}.
     temp_min : float
         Start temperature for thermal properties calculations, in K. Default is 0.0.
@@ -98,7 +98,7 @@ class Phonons(BaseCalculation):
     write_full : bool
         Whether to maximize information written in various output files.
         Default is True.
-    file_prefix : Optional[PathLike]
+    file_prefix : PathLike | None
         Prefix for output filenames. Default is inferred from chemical formula of the
         structure.
     enable_progress_bar : bool
@@ -173,34 +173,34 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[Atoms]
+        struct : Atoms | None
             ASE Atoms structure to calculate phonons for. Required if `struct_path` is
             None. Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to calculate phonons for. Required if `struct` is None.
             Default is None.
         arch : Architectures
             MLIP architecture to use for calculations. Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is -1.
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
-        calcs : Optional[MaybeSequence[PhononCalcs]]
+        calcs : MaybeSequence[PhononCalcs] | None
             Phonon calculations to run. Default calculates force constants only.
         supercell : MaybeList[int]
             The size of a supercell for calculation, or the supercell itself.
@@ -221,7 +221,7 @@ def __init__(
         minimize : bool
             Whether to perform geometry optimisation before calculating phonons.
             Default is False.
-        minimize_kwargs : Optional[dict[str, Any]]
+        minimize_kwargs : dict[str, Any] | None
             Keyword arguments to pass to geometry optimizer. Default is {}.
         temp_min : float
             Start temperature for thermal calculations, in K. Default is 0.0.
@@ -240,7 +240,7 @@ def __init__(
         write_full : bool
             Whether to maximize information written in various output files.
             Default is True.
-        file_prefix : Optional[PathLike]
+        file_prefix : PathLike | None
             Prefix for output filenames. Default is inferred from structure name, or
             chemical formula of the structure.
         enable_progress_bar : bool
@@ -373,7 +373,7 @@ def calc_force_constants(
 
         Parameters
         ----------
-        write_force_consts : Optional[bool]
+        write_force_consts : bool | None
             Whether to write out results to file. Default is self.write_results.
         **kwargs
             Additional keyword arguments to pass to `write_force_constants`.
@@ -448,13 +448,13 @@ def write_force_constants(
 
         Parameters
         ----------
-        phonopy_file : Optional[PathLike]
+        phonopy_file : PathLike | None
             Name of yaml file to save params of phonopy and optionally force constants.
             Default is inferred from `file_prefix`.
-        force_consts_to_hdf5 : Optional[bool]
+        force_consts_to_hdf5 : bool | None
             Whether to save the force constants separately to an hdf5 file. Default is
             self.force_consts_to_hdf5.
-        force_consts_file : Optional[PathLike]
+        force_consts_file : PathLike | None
             Name of hdf5 file to save force constants. Unused if `force_consts_to_hdf5`
             is False. Default is inferred from `file_prefix`.
         """
@@ -488,7 +488,7 @@ def calc_bands(self, write_bands: bool | None = None, **kwargs) -> None:
 
         Parameters
         ----------
-        write_bands : Optional[bool]
+        write_bands : bool | None
             Whether to write out results to file. Default is self.write_results.
         **kwargs
             Additional keyword arguments to pass to `write_bands`.
@@ -516,12 +516,12 @@ def write_bands(
 
         Parameters
         ----------
-        bands_file : Optional[PathLike]
+        bands_file : PathLike | None
             Name of yaml file to save band structure. Default is inferred from
             `file_prefix`.
-        save_plots : Optional[bool]
+        save_plots : bool | None
             Whether to save plot to file. Default is self.plot_to_file.
-        plot_file : Optional[PathLike]
+        plot_file : PathLike | None
             Name of svg file if saving band structure plot. Default is inferred from
             `file_prefix`.
         """
@@ -558,9 +558,9 @@ def calc_thermal_props(
 
         Parameters
         ----------
-        mesh : Optional[tuple[int, int, int]]
+        mesh : tuple[int, int, int] | None
             Mesh for sampling. Default is self.mesh.
-        write_thermal : Optional[bool]
+        write_thermal : bool | None
             Whether to write out thermal properties to file. Default is
             self.write_results.
         **kwargs
@@ -606,7 +606,7 @@ def write_thermal_props(self, thermal_file: PathLike | None = None) -> None:
 
         Parameters
         ----------
-        thermal_file : Optional[PathLike]
+        thermal_file : PathLike | None
             Name of data file to save thermal properties. Default is inferred from
             `file_prefix`.
         """
@@ -640,9 +640,9 @@ def calc_dos(
 
         Parameters
         ----------
-        mesh : Optional[tuple[int, int, int]]
+        mesh : tuple[int, int, int] | None
             Mesh for sampling. Default is self.mesh.
-        write_dos : Optional[bool]
+        write_dos : bool | None
             Whether to write out results to file. Default is True.
         **kwargs
             Additional keyword arguments to pass to `write_dos`.
@@ -690,17 +690,17 @@ def write_dos(
 
         Parameters
         ----------
-        dos_file : Optional[PathLike]
+        dos_file : PathLike | None
             Name of data file to save the calculated DOS. Default is inferred from
             `file_prefix`.
-        plot_to_file : Optional[bool]
+        plot_to_file : bool | None
             Whether to save plot to file. Default is self.plot_to_file.
-        plot_file : Optional[PathLike]
+        plot_file : PathLike | None
             Name of svg file if saving plot of the DOS. Default is inferred from
             `file_prefix`.
         plot_bands : bool
             Whether to plot the band structure and DOS together. Default is True.
-        plot_bands_file : Optional[PathLike]
+        plot_bands_file : PathLike | None
             Name of svg file if saving plot of the band structure and DOS.
             Default is inferred from `file_prefix`.
         """
@@ -747,9 +747,9 @@ def calc_pdos(
 
         Parameters
         ----------
-        mesh : Optional[tuple[int, int, int]]
+        mesh : tuple[int, int, int] | None
             Mesh for sampling. Default is self.mesh.
-        write_pdos : Optional[bool]
+        write_pdos : bool | None
             Whether to write out results to file. Default is self.write_results.
         **kwargs
             Additional keyword arguments to pass to `write_pdos`.
@@ -797,12 +797,12 @@ def write_pdos(
 
         Parameters
         ----------
-        pdos_file : Optional[PathLike]
+        pdos_file : PathLike | None
             Name of file to save the calculated PDOS. Default is inferred from
             `file_prefix`.
-        plot_to_file : Optional[bool]
+        plot_to_file : bool | None
             Whether to save plot to file. Default is self.plot_to_file.
-        plot_file : Optional[PathLike]
+        plot_file : PathLike | None
             Name of svg file if saving plot of the calculated PDOS. Default is inferred
             from `file_prefix`.
         """
diff --git a/janus_core/calculations/single_point.py b/janus_core/calculations/single_point.py
index a182e530..0fcb1b95 100644
--- a/janus_core/calculations/single_point.py
+++ b/janus_core/calculations/single_point.py
@@ -31,10 +31,10 @@ class SinglePoint(BaseCalculation):
 
     Parameters
     ----------
-    struct : Optional[MaybeSequence[Atoms]]
+    struct : MaybeSequence[Atoms] | None
         ASE Atoms structure(s) to simulate. Required if `struct_path` is None.
         Default is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to simulate. Required if `struct` is None.
         Default is None.
     arch : Architectures
@@ -42,29 +42,29 @@ class SinglePoint(BaseCalculation):
         Default is "mace_mp".
     device : Devices
         Device to run model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
     read_kwargs : ASEReadArgs
         Keyword arguments to pass to ase.io.read. By default,
         read_kwargs["index"] is ":".
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures. Default is None.
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
     properties : MaybeSequence[Properties]
         Physical properties to calculate. If not specified, "energy",
         "forces", and "stress" will be returned.
     write_results : bool
         True to write out structure with results of calculations. Default is False.
-    write_kwargs : Optional[OutputKwargs]
+    write_kwargs : OutputKwargs | None
         Keyword arguments to pass to ase.io.write if saving structure with results of
         calculations. Default is {}.
 
@@ -103,10 +103,10 @@ def __init__(
 
         Parameters
         ----------
-        struct : Optional[MaybeSequence[Atoms]]
+        struct : MaybeSequence[Atoms] | None
             ASE Atoms structure(s) to simulate. Required if `struct_path`
             is None. Default is None.
-        struct_path : Optional[PathLike]
+        struct_path : PathLike | None
             Path of structure to simulate. Required if `struct` is None.
             Default is None.
         arch : Architectures
@@ -114,29 +114,29 @@ def __init__(
             Default is "mace_mp".
         device : Devices
             Device to run MLIP model on. Default is "cpu".
-        model_path : Optional[PathLike]
+        model_path : PathLike | None
             Path to MLIP model. Default is `None`.
-        read_kwargs : Optional[ASEReadArgs]
+        read_kwargs : ASEReadArgs | None
             Keyword arguments to pass to ase.io.read. By default,
             read_kwargs["index"] is ":".
-        calc_kwargs : Optional[dict[str, Any]]
+        calc_kwargs : dict[str, Any] | None
             Keyword arguments to pass to the selected calculator. Default is {}.
-        set_calc : Optional[bool]
+        set_calc : bool | None
             Whether to set (new) calculators for structures. Default is None.
         attach_logger : bool
             Whether to attach a logger. Default is False.
-        log_kwargs : Optional[dict[str, Any]]
+        log_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_logger`. Default is {}.
         track_carbon : bool
             Whether to track carbon emissions of calculation. Default is True.
-        tracker_kwargs : Optional[dict[str, Any]]
+        tracker_kwargs : dict[str, Any] | None
             Keyword arguments to pass to `config_tracker`. Default is {}.
         properties : MaybeSequence[Properties]
             Physical properties to calculate. If not specified, "energy",
             "forces", and "stress" will be returned.
         write_results : bool
             True to write out structure with results of calculations. Default is False.
-        write_kwargs : Optional[OutputKwargs],
+        write_kwargs : OutputKwargs | None
             Keyword arguments to pass to ase.io.write if saving structure with results
             of calculations. Default is {}.
         """
diff --git a/janus_core/helpers/log.py b/janus_core/helpers/log.py
index cfa9845d..bd224327 100644
--- a/janus_core/helpers/log.py
+++ b/janus_core/helpers/log.py
@@ -18,10 +18,10 @@ class YamlFormatter(logging.Formatter):  # numpydoc ignore=PR02
 
     Parameters
     ----------
-    fmt : Optional[str]
+    fmt : str | None
         A format string in the given style for the logged output as a whole. Default is
         defined by `FORMAT`.
-    datefmt : Optional[str]
+    datefmt : str | None
         A format string in the given style for the date/time portion of the logged
         output. Default is taken from logging.Formatter.formatTime().
     style : Literal['%', '{', '$']
@@ -30,7 +30,7 @@ class YamlFormatter(logging.Formatter):  # numpydoc ignore=PR02
     validate : bool
         If True, incorrect or mismatched fmt and style will raise a ValueError. Default
         is True.
-    defaults : Optional[dict[str, logging.Any]]
+    defaults : dict[str, logging.Any] | None
          A dictionary with default values to use in custom fields. Default is None.
     *args
         Arguments to pass to logging.Formatter.__init__.
@@ -113,7 +113,7 @@ def config_logger(
     ----------
     name : str
         Name of logger. Default is None.
-    filename : Optional[str]
+    filename : str | None
         Name of log file if writing logs. Default is None.
     level : LogLevel
         Threshold for logger. Default is logging.INFO.
@@ -127,7 +127,7 @@ def config_logger(
 
     Returns
     -------
-    Optional[logging.Logger]
+    logging.Logger | None
         Configured logger if `filename` has been specified.
     """
     if filename:
@@ -166,7 +166,7 @@ def config_tracker(
 
     Parameters
     ----------
-    janus_logger : Optional[logging.Logger]
+    janus_logger : logging.Logger | None
         Logger for codecarbon output.
     track_carbon : bool
         Whether to track carbon emissions for calculation. Default is True.
@@ -179,7 +179,7 @@ def config_tracker(
 
     Returns
     -------
-    Optional[OfflineEmissionsTracker]
+    OfflineEmissionsTracker | None
         Configured offline codecarbon tracker, if logger is specified.
     """
     if janus_logger and track_carbon:
diff --git a/janus_core/helpers/mlip_calculators.py b/janus_core/helpers/mlip_calculators.py
index e8b48020..2308c3e5 100644
--- a/janus_core/helpers/mlip_calculators.py
+++ b/janus_core/helpers/mlip_calculators.py
@@ -29,14 +29,14 @@ def _set_model_path(
 
     Parameters
     ----------
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP file.
-    kwargs : Optional[dict[str, Any]]
+    kwargs : dict[str, Any] | None
         Dictionary of additional keyword arguments passed to the selected calculator.
 
     Returns
     -------
-    Optional[PathLike | torch.nn.Module]
+    PathLike | torch.nn.Module | None
         Path to MLIP model file, loaded model, or None.
     """
     kwargs = kwargs if kwargs else {}
@@ -83,7 +83,7 @@ def choose_calculator(
         MLIP architecture. Default is "mace".
     device : Devices
         Device to run calculator on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP file.
     **kwargs
         Additional keyword arguments passed to the selected calculator.
diff --git a/janus_core/helpers/struct_io.py b/janus_core/helpers/struct_io.py
index bf877610..9cdc04f4 100644
--- a/janus_core/helpers/struct_io.py
+++ b/janus_core/helpers/struct_io.py
@@ -77,15 +77,15 @@ def attach_calculator(
 
     Parameters
     ----------
-    struct : Optional[MaybeSequence[Atoms]]
+    struct : MaybeSequence[Atoms] | None
         ASE Atoms structure(s) to attach calculators to.
     arch : Architectures
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
     """
     calc_kwargs = calc_kwargs if calc_kwargs else {}
@@ -122,10 +122,10 @@ def input_structs(
 
     Parameters
     ----------
-    struct : Optional[MaybeSequence[Atoms]]
+    struct : MaybeSequence[Atoms] | None
         ASE Atoms structure(s) to simulate. Required if `struct_path` is None. Default
         is None.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure to simulate. Required if `struct` is None. Default is None.
     read_kwargs : ASEReadArgs
         Keyword arguments to pass to ase.io.read. Default is {}.
@@ -135,15 +135,15 @@ def input_structs(
         MLIP architecture to use for calculations. Default is "mace_mp".
     device : Devices
         Device to run model on. Default is "cpu".
-    model_path : Optional[PathLike]
+    model_path : PathLike | None
         Path to MLIP model. Default is `None`.
-    calc_kwargs : Optional[dict[str, Any]]
+    calc_kwargs : dict[str, Any] | None
         Keyword arguments to pass to the selected calculator. Default is {}.
-    set_calc : Optional[bool]
+    set_calc : bool | None
         Whether to set (new) calculators for structures.  Default is True if
         `struct_path` is specified or `struct` is missing calculators, else default is
         False.
-    logger : Optional[logging.Logger]
+    logger : logging.Logger | None
         Logger if log file has been specified. Default is None.
 
     Returns
@@ -232,7 +232,7 @@ def output_structs(
     ----------
     images : MaybeSequence[Atoms]
         Atoms object or a list of Atoms objects to interact with.
-    struct_path : Optional[PathLike]
+    struct_path : PathLike | None
         Path of structure being simulated. If specified, the file stem is added to the
         info dict under "system_name". Default is None.
     set_info : bool
@@ -244,7 +244,7 @@ def output_structs(
     invalidate_calc : bool
         Whether to remove all calculator results after copying properties to info dict.
         Default is False.
-    write_kwargs : Optional[ASEWriteArgs]
+    write_kwargs : ASEWriteArgs | None
         Keyword arguments passed to ase.io.write. Default is {}.
     """
     # Separate kwargs for output_structs from kwargs for ase.io.write
diff --git a/janus_core/helpers/utils.py b/janus_core/helpers/utils.py
index 46f140a1..3153fac4 100644
--- a/janus_core/helpers/utils.py
+++ b/janus_core/helpers/utils.py
@@ -130,7 +130,7 @@ def _build_filename(
             Extra components to add to suffix (joined with hyphens).
         filename : PathLike | None
             Filename to use, if specified. Default is None.
-        prefix_override : Optional[str]
+        prefix_override : str | None
             Replace file_prefix if not None.
 
         Returns
@@ -157,7 +157,7 @@ def none_to_dict(dictionaries: Sequence[dict | None]) -> Generator[dict, None, N
 
     Parameters
     ----------
-    dictionaries : Sequence[Optional[dict]]
+    dictionaries : Sequence[dict | None]
         Sequence of dictionaries that could be None.
 
     Yields
@@ -222,7 +222,7 @@ def write_table(
 
     Returns
     -------
-    Optional[StringIO]
+    StringIO | None
         If no file given write columns to StringIO.
 
     Notes
diff --git a/janus_core/processing/post_process.py b/janus_core/processing/post_process.py
index 08af0e8d..044b8d02 100644
--- a/janus_core/processing/post_process.py
+++ b/janus_core/processing/post_process.py
@@ -64,9 +64,9 @@ def compute_rdf(
     ----------
     data : MaybeSequence[Atoms]
         Dataset to compute RDF of.
-    ana : Optional[Analysis]
+    ana : Analysis | None
         ASE Analysis object for data reuse.
-    filenames : Optional[MaybeSequence[PathLike]]
+    filenames : MaybeSequence[PathLike] | None
         Filenames to output data to. Must match number of RDFs computed.
     by_elements : bool
         Split RDF into pairwise by elements group. Default is False.
@@ -76,7 +76,7 @@ def compute_rdf(
         Maximum distance of RDF.
     nbins : int
         Number of bins to divide RDF.
-    elements : Optional[MaybeSequence[Union[int, str]]]
+    elements : MaybeSequence[int | str] | None
         Make partial RDFs. If `by_elements` is true will filter to
         only display pairs in list.
     index : SliceLike
@@ -84,13 +84,13 @@ def compute_rdf(
         `index` if `int`,
         `start`, `stop`, `step` if `tuple`,
         `slice` if `slice` or `range`.
-    volume : Optional[float]
+    volume : float | None
         Volume of cell for normalisation. Only needs to be provided
         if aperiodic cell. Default is (2*rmax)**3.
 
     Returns
     -------
-    Union[NDArray[float64], dict[tuple[str, str], NDArray[float64]]]
+    NDArray[float64] | dict[tuple[str, str] | NDArray[float64]]
         If `by_elements` is true returns a `dict` of RDF by element pairs.
         Otherwise returns RDF of total system filtered by elements.
     """
@@ -200,7 +200,7 @@ def compute_vaf(
     ----------
     data : Sequence[Atoms]
         Dataset to compute VAF of.
-    filenames : Optional[MaybeSequence[PathLike]]
+    filenames : MaybeSequence[PathLike] | None
         If present, dump resultant VAF to file.
     use_velocities : bool
         Compute VAF using velocities rather than momenta.
@@ -211,7 +211,7 @@ def compute_vaf(
     index : SliceLike
         Images to analyze as `start`, `stop`, `step`.
         Default is all images.
-    filter_atoms : MaybeSequence[MaybeSequence[Optional[int]]]
+    filter_atoms : MaybeSequence[MaybeSequence[int | None]]
         Compute the VAF averaged over subsets of the system.
         Default is all atoms.
     time_step : float
diff --git a/janus_core/training/train.py b/janus_core/training/train.py
index 6962fce6..72bb5610 100644
--- a/janus_core/training/train.py
+++ b/janus_core/training/train.py
@@ -58,16 +58,16 @@ def train(
     ----------
     mlip_config : PathLike
         Configuration file to pass to MLIP.
-    req_file_keys : Optional[list[PathLike]]
+    req_file_keys : list[PathLike] | None
         List of files that must exist if defined in the configuration file.
         Default is ["train_file", "test_file", "valid_file", "statistics_file"].
     attach_logger : bool
         Whether to attach a logger. Default is False.
-    log_kwargs : Optional[dict[str, Any]]
+    log_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_logger`. Default is {}.
     track_carbon : bool
         Whether to track carbon emissions of calculation. Default is True.
-    tracker_kwargs : Optional[dict[str, Any]]
+    tracker_kwargs : dict[str, Any] | None
         Keyword arguments to pass to `config_tracker`. Default is {}.
     """
     (log_kwargs, tracker_kwargs) = none_to_dict((log_kwargs, tracker_kwargs))
diff --git a/tests/utils.py b/tests/utils.py
index acd0188b..0216be40 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -24,7 +24,7 @@ def read_atoms(path: Path) -> Atoms | None:
 
     Returns
     -------
-    Union[Atoms, None]
+    Atoms | None
         Atoms structure read from file, or None is any Exception is thrown.
     """
     assert path.exists()