`momentGW.gw`

Spin-restricted one-shot GW via self-energy moment constraints for molecular systems.

Module Contents

momentGW.gw.kernel(gw, nmom_max, moments=None, integrals=None)

Moment-constrained one-shot GW.

Parameters:

gw (BaseGW) – GW object.
nmom_max (int) – Maximum moment number to calculate.
moments (tuple of numpy.ndarray, optional) – Tuple of (hole, particle) moments, if passed then they will be used instead of calculating them. Default value is None.
integrals (BaseIntegrals, optional) – Integrals object. If None, generate from scratch. Default value is None.

Returns:

conv (bool) – Convergence flag. Always True for GW, returned for compatibility with other GW methods.
gf (dyson.Lehmann) – Green’s function object.
se (dyson.Lehmann) – Self-energy object.
qp_energy (numpy.ndarray) – Quasiparticle energies. Always None for GW, returned for compatibility with other GW methods.

Notes

This approach is described in [1]_.

References

class momentGW.gw.GW(mf, **kwargs)

Bases: momentGW.base.BaseGW

Spin-restricted one-shot GW via self-energy moment constraints for molecules.

Parameters:

mf (pyscf.scf.SCF) – PySCF mean-field class.
diagonal_se (bool, optional) – If True, use a diagonal approximation in the self-energy. Default value is False.
polarizability (str, optional) – Type of polarizability to use, can be one of (“drpa”, “drpa-exact”, “dtda”, “thc-dtda”). Default value is `”drpa”.
npoints (int, optional) – Number of numerical integration points. Default value is 48.
optimise_chempot (bool, optional) – If True, optimise the chemical potential by shifting the position of the poles in the self-energy relative to those in the Green’s function. Default value is False.
fock_loop (bool, optional) – If True, self-consistently renormalise the density matrix according to the updated Green’s function. Default value is False.
fock_opts (dict, optional) – Dictionary of options passed to the Fock loop. For more details see momentGW.fock.
compression (str, optional) – Blocks of the ERIs to use as a metric for compression. Can be one or more of (“oo”, “ov”, “vv”, “ia”) which can be passed as a comma-separated string. “oo”, “ov” and “vv” refer to compression on the initial ERIs, whereas “ia” refers to compression on the ERIs entering RPA, which may change under a self-consistent scheme. Default value is “ia”.
compression_tol (float, optional) – Tolerance for the compression. Default value is 1e-10.
thc_opts (dict, optional) – Dictionary of options to be used for THC calculations. Current implementation requires a filepath to import the THC integrals.

Notes

This approach is described in [1]_.

References

property name: Get the method name.

property qp_energy

Get the quasiparticle energies.

Notes

For most GW methods, this simply consists of the poles of the self.gf that best overlap with the MOs, in order. In some methods such as qsGW, these two quantities are not the same.

property has_fock_loop

Get a boolean indicating whether the solver requires a Fock loop.

Notes

For most GW methods, this is simply self.fock_loop. In some methods such as qsGW, a Fock loop is required with or without self.fock_loop for the quasiparticle self-consistency, with this property acting as a hook to indicate this.

property mol: Get the molecule object.

property with_df: Get the density fitting object.

property nao: Get the number of atomic orbitals.

property nmo: Get the number of molecular orbitals.

property nocc: Get the number of occupied molecular orbitals.

property active: Get the mask to remove frozen orbitals.

property mo_energy: Get the molecular orbital energies.

property mo_energy_with_frozen: Get the molecular orbital energies with frozen orbitals.

property mo_coeff: Get the molecular orbital coefficients.

property mo_coeff_with_frozen: Get the molecular orbital coefficients with frozen orbitals.

property mo_occ: Get the molecular orbital occupation numbers.

property mo_occ_with_frozen: Get the molecular orbital occupation numbers with frozen orbitals.

build_se_static(integrals)

Build the static part of the self-energy, including the Fock matrix.

Parameters:: integrals (Integrals) – Integrals object.
Returns:: se_static – Static part of the self-energy. If self.diagonal_se, non-diagonal elements are set to zero.
Return type:: numpy.ndarray

build_se_moments(nmom_max, integrals, **kwargs)

Build the moments of the self-energy.

Parameters:

nmom_max (int) – Maximum moment number to calculate.
integrals (Integrals) – Integrals object.
**kwargs (dict, optional) – Additional keyword arguments passed to polarizability class.

Returns:

se_moments_hole (numpy.ndarray) – Moments of the hole self-energy. If self.diagonal_se, non-diagonal elements are set to zero.
se_moments_part (numpy.ndarray) – Moments of the particle self-energy. If self.diagonal_se, non-diagonal elements are set to zero.

momentGW.gw

Module Contents

`momentGW.gw`