#!/usr/bin/env python
# Copyright 2014-2018 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: Qiming Sun <osirpt.sun@gmail.com>
#
'''
Restricted coupled perturbed Hartree-Fock solver
'''
import numpy
from pyscf import lib
from pyscf.lib import logger
[docs]
def solve(fvind, mo_energy, mo_occ, h1, s1=None,
max_cycle=50, tol=1e-9, hermi=False, verbose=logger.WARN,
level_shift=0):
'''
Args:
fvind : function
Given density matrix, compute (ij|kl)D_{lk}*2 - (ij|kl)D_{jk}
Kwargs:
hermi : boolean
Whether the matrix defined by fvind is Hermitian or not.
level_shift : float
Add to diagonal terms to slightly improve the convergence speed of
Krylov solver
'''
if s1 is None:
return solve_nos1(fvind, mo_energy, mo_occ, h1,
max_cycle, tol, hermi, verbose, level_shift)
else:
return solve_withs1(fvind, mo_energy, mo_occ, h1, s1,
max_cycle, tol, hermi, verbose, level_shift)
kernel = solve
# h1 shape is (:,nvir,nocc)
[docs]
def solve_nos1(fvind, mo_energy, mo_occ, h1,
max_cycle=50, tol=1e-9, hermi=False, verbose=logger.WARN,
level_shift=0):
'''For field independent basis. First order overlap matrix is zero
Kwargs:
level_shift : float
Add to diagonal terms to slightly improve the convergence speed of
Krylov solver
'''
assert not hermi
log = logger.new_logger(verbose=verbose)
t0 = (logger.process_clock(), logger.perf_counter())
e_a = mo_energy[mo_occ==0]
e_i = mo_energy[mo_occ>0]
e_ai = 1 / (e_a[:,None] + level_shift - e_i)
mo1base = h1 * -e_ai
nvir, nocc = e_ai.shape
def vind_vo(mo1):
mo1 = mo1.reshape(-1, nvir, nocc)
v = fvind(mo1).reshape(-1, nvir, nocc)
if level_shift != 0:
v -= mo1 * level_shift
v *= e_ai
return v.reshape(-1, nvir*nocc)
mo1 = lib.krylov(vind_vo, mo1base.reshape(-1, nvir*nocc),
tol=tol, max_cycle=max_cycle, hermi=hermi, verbose=log)
log.timer('krylov solver in CPHF', *t0)
return mo1.reshape(h1.shape), None
# h1 shape is (:,nocc+nvir,nocc)
[docs]
def solve_withs1(fvind, mo_energy, mo_occ, h1, s1,
max_cycle=50, tol=1e-9, hermi=False, verbose=logger.WARN,
level_shift=0):
'''For field dependent basis. First order overlap matrix is non-zero.
The first order orbitals are set to
C^1_{ij} = -1/2 S1
e1 = h1 - s1*e0 + (e0_j-e0_i)*c1 + vhf[c1]
Kwargs:
level_shift : float
Add to diagonal terms to slightly improve the convergence speed of
Krylov solver
Returns:
First order orbital coefficients (in MO basis) and first order orbital
energy matrix
'''
assert not hermi
log = logger.new_logger(verbose=verbose)
t0 = (logger.process_clock(), logger.perf_counter())
occidx = mo_occ > 0
viridx = mo_occ == 0
e_a = mo_energy[viridx]
e_i = mo_energy[occidx]
e_ai = 1 / (e_a[:,None] + level_shift - e_i)
nvir, nocc = e_ai.shape
nmo = nocc + nvir
s1 = s1.reshape(-1,nmo,nocc)
hs = mo1base = h1.reshape(-1,nmo,nocc) - s1*e_i
mo1base = hs.copy()
mo1base[:,viridx] *= -e_ai
mo1base[:,occidx] = -s1[:,occidx] * .5
def vind_vo(mo1):
mo1 = mo1.reshape(-1, nmo, nocc)
v = fvind(mo1).reshape(-1, nmo, nocc)
if level_shift != 0:
v -= mo1 * level_shift
v[:,viridx,:] *= e_ai
v[:,occidx,:] = 0
return v.reshape(-1, nmo*nocc)
mo1 = lib.krylov(vind_vo, mo1base.reshape(-1, nmo*nocc),
tol=tol, max_cycle=max_cycle, hermi=hermi, verbose=log)
mo1 = mo1.reshape(-1, nmo, nocc)
mo1[:,occidx] = mo1base[:,occidx]
log.timer('krylov solver in CPHF', *t0)
hs += fvind(mo1).reshape(-1, nmo, nocc)
mo1[:,viridx] = hs[:,viridx] / (e_i - e_a[:,None])
# mo_e1 has the same symmetry as the first order Fock matrix (hermitian or
# anti-hermitian). mo_e1 = v1mo - s1*lib.direct_sum('i+j->ij',e_i,e_i)
mo_e1 = hs[:,occidx,:]
mo_e1 += mo1[:,occidx] * (e_i[:,None] - e_i)
if h1.ndim == 3:
return mo1, mo_e1
else:
assert h1.ndim == 2
return mo1[0], mo_e1[0]
