Adding custom basis set interface

pyqint/molecule.py

@@ -150,4 +150,7 @@ def get_nuclei(self):
             self.__charges[aidx] = getattr(el, atom[0])
             self.__nuclei.append([atom[1], self.__charges[aidx]])
 
+        # populate number of electrons
+        self.__nelec = np.sum(self.__charges)
+
         return self.__nuclei

tests/test_custom_basis_set.py

@@ -0,0 +1,27 @@
+import unittest
+from pyqint import Molecule, cgf, HF
+import numpy as np
+
+class TestCustomBasisSet(unittest.TestCase):
+
+    def test_custom_basis_set_h2(self):
+        mol = Molecule()
+        mol.add_atom('H', 0.0000, 0.0000, 0.3561150187, unit='angstrom')
+        mol.add_atom('H', 0.0000, 0.0000, -0.3561150187, unit='angstrom')        
+        nuclei = mol.get_nuclei()
+
+        cgfs = []
+        for n in nuclei:
+            _cgf = cgf(n[0])
+
+            _cgf.add_gto(0.154329, 3.425251, 0, 0, 0)
+            _cgf.add_gto(0.535328, 0.623914, 0, 0, 0)
+            _cgf.add_gto(0.444635, 0.168855, 0, 0, 0)
+
+            cgfs.append(_cgf)
+
+        res = HF().rhf(mol, basis=cgfs)
+        np.testing.assert_almost_equal(res['energy'], -1.1175059, 5)
+
+if __name__ == '__main__':
+    unittest.main()