fix assert bug for kpoints weight summation (#60)

 add abs to assert

dptb/utils/make_kpoints.py

@@ -126,6 +126,7 @@ def gamma_center(meshgrid=[1,1,1]):
 
 
 
+
 def kmesh_sampling(meshgrid=[1,1,1], is_gamma_center=True):
     """ Generate k-points using Monkhorst-Pack method based on given meshgrid. The k-points are centered at Gamma point by default.
      
@@ -207,7 +208,7 @@ def time_symmetry_reduce(meshgrid=[1,1,1], is_gamma_center=True):
     k_points_with_tr = k_points_with_tr[k_sort_indx]
     kweight = np.array(kweight)/len(k_points) # normalize the weight to one
     kweight = kweight[k_sort_indx]
-    assert kweight.sum() == 1, "The sum of weight is not 1.0"
+    assert abs(kweight.sum() - 1.0) < 1e-5, "The sum of weight is not 1.0"
 
     return k_points_with_tr, kweight