# Copyright 2014-2020 The PySCF Developers. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Author: Oliver Backhouse <olbackhouse@gmail.com>
# George Booth <george.booth@kcl.ac.uk>
#
'''
Auxiliary second-order Green's function perturbation theory
===========================================================
The AGF2 method permits the computation of quasiparticle excitations and
ground-state properties at the AGF2(None,0) level.
When using results of this code for publications, please cite the follow papers:
"Wave function perspective and efficient truncation of renormalized second-order perturbation theory", O. J. Backhouse, M. Nusspickel and G. H. Booth, J. Chem. Theory Comput., 16, 1090 (2020).
"Efficient excitations and spectra within a perturbative renormalization approach", O. J. Backhouse and G. H. Booth, J. Chem. Theory Comput., 16, 6294 (2020).
Simple usage::
>>> from pyscf import gto, scf, agf2
>>> mol = gto.M(atom='H 0 0 0; H 0 0 1')
>>> mf = scf.RHF(mol).run()
>>> gf2 = agf2.AGF2(mf).run()
>>> gf2.ipagf2()
:func:`agf2.AGF2` returns an instance of AGF2 class. Valid parameters to
control the AGF2 method are:
verbose : int
Print level. Default value equals to :class:`Mole.verbose`
max_memory : float or int
Allowed memory in MB. Default value equals to :class:`Mole.max_memory`
conv_tol : float
Convergence threshold for AGF2 energy. Default value is 1e-7
conv_tol_rdm1 : float
Convergence threshold for first-order reduced density matrix.
Default value is 1e-6.
conv_tol_nelec : float
Convergence threshold for the number of electrons. Default
value is 1e-6.
max_cycle : int
Maximum number of AGF2 iterations. Default value is 50.
max_cycle_outer : int
Maximum number of outer Fock loop iterations. Default
value is 20.
max_cycle_inner : int
Maximum number of inner Fock loop iterations. Default
value is 50.
weight_tol : float
Threshold in spectral weight of auxiliaries to be considered
zero. Default 1e-11.
diis_space : int
DIIS space size for Fock loop iterations. Default value is 6.
diis_min_space :
Minimum space of DIIS. Default value is 1.
Saved result
e_corr : float
AGF2 correlation energy
e_tot : float
Total energy (HF + correlation)
e_1b : float
One-body part of :attr:`e_tot`
e_2b : float
Two-body part of :attr:`e_tot`
e_init : float
Initial correlation energy (truncated MP2)
converged : bool
Whether convergence was successful
se : SelfEnergy
Auxiliaries of the self-energy
gf : GreensFunction
Auxiliaries of the Green's function
'''
from pyscf import scf, lib
from pyscf.agf2 import aux_space, ragf2, uagf2, dfragf2, dfuagf2, ragf2_slow, uagf2_slow
from pyscf.agf2.aux_space import AuxiliarySpace, GreensFunction, SelfEnergy
# Backwards compatibility:
aux = aux_space
[docs]
def AGF2(mf, nmom=(None,0), frozen=None, mo_energy=None, mo_coeff=None, mo_occ=None):
if isinstance(mf, scf.uhf.UHF):
return UAGF2(mf, nmom, frozen, mo_energy, mo_coeff, mo_occ)
elif isinstance(mf, scf.rohf.ROHF):
lib.logger.warn(mf, 'RAGF2 method does not support ROHF reference. '
'Converting to UHF and using UAGF2.')
mf = mf.to_uhf()
return UAGF2(mf, nmom, frozen, mo_energy, mo_coeff, mo_occ)
elif isinstance(mf, scf.rhf.RHF):
return RAGF2(mf, nmom, frozen, mo_energy, mo_coeff, mo_occ)
else:
raise RuntimeError('AGF2 code only supports RHF, ROHF and UHF references')
AGF2.__doc__ = ragf2.RAGF2.__doc__
[docs]
def RAGF2(mf, nmom=(None,0), frozen=None, mo_energy=None, mo_coeff=None, mo_occ=None):
if nmom != (None,0): # redundant
if nmom[1] == 0 and nmom[0] != 0:
nmom = (None,0)
if nmom != (None,0) and getattr(mf, 'with_df', None) is not None:
raise RuntimeError('AGF2 with custom moment orders does not '
'density fitting.')
elif nmom != (None,0):
lib.logger.warn(mf, 'AGF2 called with custom moment orders - '
'falling back on _slow implementations.')
return ragf2_slow.RAGF2(mf, nmom, frozen, mo_energy, mo_coeff, mo_occ)
elif getattr(mf, 'with_df', None) is not None:
return dfragf2.DFRAGF2(mf, frozen, mo_energy, mo_coeff, mo_occ)
else:
return ragf2.RAGF2(mf, frozen, mo_energy, mo_coeff, mo_occ)
RAGF2.__doc__ = ragf2.RAGF2.__doc__
[docs]
def UAGF2(mf, nmom=(None,0), frozen=None, mo_energy=None, mo_coeff=None, mo_occ=None):
if nmom != (None,0): # redundant
if nmom[1] == 0 and nmom[0] != 0:
nmom = (None,0)
if nmom != (None,0) and getattr(mf, 'with_df', None) is not None:
raise RuntimeError('AGF2 with custom moment orders does not '
'density fitting.')
elif nmom != (None,0):
lib.logger.warn(mf, 'AGF2 called with custom moment orders - '
'falling back on _slow implementations.')
return uagf2_slow.UAGF2(mf, nmom, frozen, mo_energy, mo_coeff, mo_occ)
elif getattr(mf, 'with_df', None) is not None:
return dfuagf2.DFUAGF2(mf, frozen, mo_energy, mo_coeff, mo_occ)
else:
return uagf2.UAGF2(mf, frozen, mo_energy, mo_coeff, mo_occ)
UAGF2.__doc__ = uagf2.UAGF2.__doc__
