Included covalent radii information

README.md

@@ -88,6 +88,10 @@ Atomic weights are reported in the following publication:
 
 > Meija, J., Coplen, T., Berglund, M., et al. (2016). *Atomic weights of the elements 2013* (IUPAC Technical Report). Pure and Applied Chemistry, 88(3), pp. 265-291. Retrieved 30 Nov. 2016, [DOI:10.1515/pac-2015-0305](https://doi.org/10.1515/pac-2015-0305)
 
+Covalent radii are reported in the following article:
+
+> Cordero, B. et al. (2008). *Covalent radii revisited*. Dalton Transactions, issue 21, pp. 2832-2838. The Royal Society of Chemistry. [DOI: 10.1039/B801115j](https://dx.doi.org/10.1039/B801115J)
+
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crystals/atom_data.py

@@ -514,3 +514,104 @@
 ]
 
 ELEM_TO_MAGMOM = dict(zip(chemical_symbols, ground_state_magnetic_moments))
+
+# from Cordero et al, 'Covalent radii revisited' (2008).
+# Dalton Transactions. DOI: 10.1039/B801115J
+covalent_radii = {
+    "H": 0.31,
+    "He": 0.28,
+    "Li": 1.28,
+    "Be": 0.96,
+    "B": 0.84,
+    "C": 0.76,
+    "N": 0.71,
+    "O": 0.66,
+    "F": 0.57,
+    "Ne": 0.58,
+    "Na": 1.66,
+    "Mg": 1.41,
+    "Al": 1.21,
+    "Si": 1.11,
+    "P": 1.07,
+    "S": 1.05,
+    "Cl": 1.02,
+    "Ar": 1.06,
+    "K": 2.03,
+    "Ca": 1.76,
+    "Sc": 1.7,
+    "Ti": 1.6,
+    "V": 1.53,
+    "Cr": 1.39,
+    "Mn": 1.61,
+    "Fe": 1.52,
+    "Co": 1.5,
+    "Ni": 1.24,
+    "Cu": 1.32,
+    "Zn": 1.22,
+    "Ga": 1.22,
+    "Ge": 1.2,
+    "As": 1.19,
+    "Se": 1.2,
+    "Br": 1.2,
+    "Kr": 1.16,
+    "Rb": 2.2,
+    "Sr": 1.95,
+    "Y": 1.9,
+    "Zr": 1.75,
+    "Nb": 1.64,
+    "Mo": 1.54,
+    "Tc": 1.47,
+    "Ru": 1.46,
+    "Rh": 1.42,
+    "Pd": 1.39,
+    "Ag": 1.45,
+    "Cd": 1.44,
+    "In": 1.42,
+    "Sn": 1.39,
+    "Sb": 1.39,
+    "Te": 1.38,
+    "I": 1.39,
+    "Xe": 1.4,
+    "Cs": 2.44,
+    "Ba": 2.15,
+    "La": 2.07,
+    "Ce": 2.04,
+    "Pr": 2.03,
+    "Nd": 2.01,
+    "Pm": 1.99,
+    "Sm": 1.98,
+    "Eu": 1.98,
+    "Gd": 1.96,
+    "Tb": 1.94,
+    "Dy": 1.92,
+    "Ho": 1.92,
+    "Er": 1.89,
+    "Tm": 1.9,
+    "Yb": 1.87,
+    "Lu": 1.87,
+    "Hf": 1.75,
+    "Ta": 1.7,
+    "W": 1.62,
+    "Re": 1.51,
+    "Os": 1.44,
+    "Ir": 1.41,
+    "Pt": 1.36,
+    "Au": 1.36,
+    "Hg": 1.32,
+    "Tl": 1.45,
+    "Pb": 1.46,
+    "Bi": 1.48,
+    "Po": 1.4,
+    "At": 1.5,
+    "Rn": 1.5,
+    "Fr": 2.6,
+    "Ra": 2.21,
+    "Ac": 2.15,
+    "Th": 2.06,
+    "Pa": 2.0,
+    "U": 1.96,
+    "Np": 1.9,
+    "Pu": 1.87,
+    "Am": 1.8,
+    "Cm": 1.69,
+}