from itertools import combinations
print('Generating %d Full CI Determinants...' % (nDet))
t = time.time()
detList = []
for alpha in combinations(range(nmo), ndocc):
for beta in combinations(range(nmo), ndocc):
detList.append(Determinant(alphaObtList=alpha, betaObtList=beta))
print('..finished generating determinants in %.3f seconds.\n' %
(time.time() - t))
print('Generating Hamiltonian Matrix...')
t = time.time()
Hamiltonian_generator = HamiltonianGenerator(H, MO)
Hamiltonian_matrix = Hamiltonian_generator.generateMatrix(detList)
print('..finished generating Matrix in %.3f seconds.\n' % (time.time() - t))
print('Diagonalizing Hamiltonian Matrix...')
t = time.time()
e_fci, wavefunctions = np.linalg.eigh(Hamiltonian_matrix)
print('..finished diagonalization in %.3f seconds.\n' % (time.time() - t))
fci_mol_e = e_fci[0] + mol.nuclear_repulsion_energy()
print('# Determinants: % 16d' % (len(detList)))
from itertools import combinations
print('Generating %d CIS singlet Determinants...' % (nDet_S + 1))
t = time.time()
occList = [i for i in range(ndocc)]
det_ref = Determinant(alphaObtList=occList, betaObtList=occList)
detList = det_ref.generateSingleExcitationsOfDet(nmo)
detList.append(det_ref)
print('..finished generating determinants in %.3f seconds.\n' % (time.time() - t))
print('Generating Hamiltonian Matrix...')
t = time.time()
Hamiltonian_generator = HamiltonianGenerator(H, MO)
Hamiltonian_matrix = Hamiltonian_generator.generateMatrix(detList)
print('..finished generating Matrix in %.3f seconds.\n' % (time.time() - t))
print('Diagonalizing Hamiltonian Matrix...')
t = time.time()
e_cis, wavefunctions = np.linalg.eigh(Hamiltonian_matrix)
print('..finished diagonalization in %.3f seconds.\n' % (time.time() - t))
print('# Determinants: % 16d' % (len(detList)))
print('SCF energy: % 16.10f' % (scf_e))