class CoupledClusterSinglesDoubles(CoupledCluster):
def __init__(self, hartree_fock, threshold=1e-12):
super().__init__(hartree_fock, threshold)
self.amplitudes_factory = SinglesDoubles(self.repulsion, self.orbital_energies, self.occupied_orbitals,
self.unoccupied_orbitals)
def calculate_singles_doubles(self):
print('*************************************************************************************************')
print('\nMP2 INITIAL GUESS')
start = time.clock()
amplitudes = self.amplitudes_factory.mp2_initial_guess()
correlation = self.singles_doubles_correlation(amplitudes)
print('MP2 CORRELATION ENERGY: ' + str(correlation) + ' a.u.')
print('TIME TAKEN: ' + str(time.clock() - start) + 's')
print('\n*************************************************************************************************')
print('\nBEGIN CCSD ITERATIONS')
start = time.clock()
previous_correlation = 0
while True:
amplitudes = self.amplitudes_factory.calculate_amplitudes(amplitudes)
correlation = self.singles_doubles_correlation(amplitudes)
delta_energy = previous_correlation - correlation
previous_correlation = correlation
print('CCSD CORRELATION ENERGY: ' + str(correlation) + ' a.u.')
if abs(delta_energy) < self.threshold:
break
print('TIME TAKEN: ' + str(time.clock() - start) + 's\n\n')
return correlation, amplitudes
def singles_doubles_correlation(self, t):
correlation = 0
for i, j, a, b in self.doubles():
correlation += self.repulsion.item(i, j, a, b) * (0.25 * t[i, j, a, b] + 0.5 * t[i, a] * t[j, b])
return correlation
def __init__(self, hartree_fock, threshold=1e-12):
super().__init__(hartree_fock, threshold)
self.amplitudes_factory = SinglesDoubles(self.repulsion, self.orbital_energies, self.occupied_orbitals,
self.unoccupied_orbitals)