openqemist.electronic_structure_solvers.ccsd_solver package

Submodules

openqemist.electronic_structure_solvers.ccsd_solver.ccsd_solver module

Perform CCSD calculation.

The electronic structure calculation employing the coupled-cluster singles and doubles (CCSD) method is done here.

class openqemist.electronic_structure_solvers.ccsd_solver.ccsd_solver.CCSDSolver[source]

Bases: openqemist.electronic_structure_solvers.electronic_structure_solver.ElectronicStructureSolver

Perform CCSD calculation.

Uses the CCSD method to solve the electronic structure problem. PySCF program will be utilized. Users can also provide a function that takes a pyscf.gto.Mole as its first argument and pyscf.scf.RHF as its second.

cc_fragment

The coupled-cluster object.

Type

pyscf.cc.CCSD

get_rdm()[source]

Calculate the 1- and 2-particle RDMs.

Calculate the CCSD reduced density matrices. The CCSD lambda equation will be solved for calculating the RDMs.

Returns

One & two-particle RDMs (cc_onerdm & cc_twordm, float64).

Return type

(numpy.array, numpy.array)

Raises

RuntimeError – If no simulation has been run.

simulate(molecule, mean_field=None)[source]

Perform the simulation (energy calculation) for the molecule.

If the mean field is not provided it is automatically calculated.

Parameters

  • molecule (pyscf.gto.Mole) – The molecule to simulate.

  • mean_field (pyscf.scf.RHF) – The mean field of the molecule.

Returns

CCSD energy (total_energy).

Return type

float64

Module contents