# Author: Artem Pulkin
# flake8: noqa
"""
This and other `_slow` modules implement the time-dependent Hartree-Fock procedure. The primary performance drawback is
that, unlike other 'fast' routines with an implicit construction of the eigenvalue problem, these modules construct
TDHF matrices explicitly via an AO-MO transformation, i.e. with a O(N^5) complexity scaling. As a result, regular
`numpy.linalg.eig` can be used to retrieve TDHF roots in a reliable fashion without any issues related to the Davidson
procedure. Several variants of TDHF are available:
* `pyscf.tdscf.rhf_slow`: the molecular implementation;
* `pyscf.pbc.tdscf.rhf_slow`: PBC (periodic boundary condition) implementation for RHF objects of `pyscf.pbc.scf`
modules;
* `pyscf.pbc.tdscf.krhf_slow_supercell`: PBC implementation for KRHF objects of `pyscf.pbc.scf` modules. Works with
an arbitrary number of k-points but has a overhead due to an effective construction of a supercell.
* `pyscf.pbc.tdscf.krhf_slow_gamma`: A Gamma-point calculation resembling the original `pyscf.pbc.tdscf.krhf`
module. Despite its name, it accepts KRHF objects with an arbitrary number of k-points but finds only few TDHF roots
corresponding to collective oscillations without momentum transfer;
* (this module) `pyscf.pbc.tdscf.krhf_slow`: PBC implementation for KRHF objects of `pyscf.pbc.scf` modules. Works with
an arbitrary number of k-points and employs k-point conservation (diagonalizes matrix blocks separately).
"""
from pyscf.pbc.tdscf import krhf_slow_supercell as td
from pyscf.tdscf import rhf_slow
from pyscf.tdscf.common_slow import mknj2i
import numpy
# Convention for these modules:
# * PhysERI, PhysERI4, PhysERI8 are 2-electron integral routines computed directly (for debug purposes), with a 4-fold
# symmetry and with an 8-fold symmetry
# * vector_to_amplitudes reshapes and normalizes the solution
# * TDRHF provides a container
[docs]
class PhysERI(td.PhysERI):
primary_driver = "full"
def __init__(self, model, frozen=None):
"""
The TDHF ERI implementation performing a full transformation of integrals to Bloch functions. No symmetries are
employed in this class. The ERIs are returned in blocks of k-points.
Args:
model (KRHF): the base model;
frozen (int, Iterable): the number of frozen valence orbitals or the list of frozen orbitals for all
k-points or multiple lists of frozen orbitals for each k-point;
"""
super(PhysERI, self).__init__(model, frozen=frozen)
[docs]
def get_k_ix(self, item, like):
"""
Retrieves block indexes: row and column.
Args:
item (str): a string of 'mknj' letters;
like (tuple): a 2-tuple with sample pair of k-points;
Returns:
Row and column indexes of a sub-block with conserving momentum.
"""
item_i = numpy.argsort(mknj2i(item))
item_code = ''.join("++--"[i] for i in item_i)
if item_code[0] == item_code[1]:
kc = self.kconserv # ++-- --++
elif item_code[0] == item_code[2]:
kc = self.kconserv.swapaxes(1, 2) # +-+- -+-+
elif item_code[1] == item_code[2]:
kc = self.kconserv.transpose(2, 0, 1) # +--+ -++-
else:
raise RuntimeError("Unknown case: {}".format(item_code))
y = kc[like]
x = kc[0, y[0]]
return x, y
[docs]
def tdhf_diag(self, block):
"""
Retrieves the merged diagonal block only with specific pairs of k-indexes (k, block[k]).
Args:
block (Iterable): a k-point pair `k2 = pair[k1]` for each k1;
Returns:
The diagonal block.
"""
return super(PhysERI, self).tdhf_diag(pairs=enumerate(block))
[docs]
def eri_mknj(self, item, pair_row, pair_column):
"""
Retrieves the merged ERI block using 'mknj' notation with pairs of k-indexes (k1, k1, k2, k2).
Args:
item (str): a 4-character string of 'mknj' letters;
pair_row (Iterable): a k-point pair `k2 = pair_row[k1]` for each k1 (row indexes in the final matrix);
pair_column (Iterable): a k-point pair `k4 = pair_row[k3]` for each k3 (column indexes in the final matrix);
Returns:
The corresponding block of ERI (phys notation).
"""
return super(PhysERI, self).eri_mknj(
item,
pairs_row=enumerate(pair_row),
pairs_column=enumerate(pair_column),
)
[docs]
class PhysERI4(PhysERI):
def __init__(self, model, frozen=None):
"""
The TDHF ERI implementation performing partial transformations of integrals to Bloch functions. A 4-fold
symmetry of complex-valued functions is employed in this class. The ERIs are returned in blocks of k-points.
Args:
model (KRHF): the base model;
frozen (int, Iterable): the number of frozen valence orbitals or the list of frozen orbitals for all
k-points or multiple lists of frozen orbitals for each k-point;
"""
td.PhysERI4.__init__.im_func(self, model, frozen=frozen)
symmetries = [
((0, 1, 2, 3), False),
((1, 0, 3, 2), False),
((2, 3, 0, 1), True),
((3, 2, 1, 0), True),
]
def __calc_block__(self, item, k):
if self.kconserv[k[:3]] == k[3]:
return td.PhysERI4.__calc_block__.im_func(self, item, k)
else:
raise ValueError("K is not conserved: {}, expected {}".format(
repr(k),
k[:3] + (self.kconserv[k[:3]],),
))
[docs]
class PhysERI8(PhysERI4):
def __init__(self, model, frozen=None):
"""
The TDHF ERI implementation performing partial transformations of integrals to Bloch functions. An 8-fold
symmetry of real-valued functions is employed in this class. The ERIs are returned in blocks of k-points.
Args:
model (KRHF): the base model;
frozen (int, Iterable): the number of frozen valence orbitals or the list of frozen orbitals for all
k-points or multiple lists of frozen orbitals for each k-point;
"""
super(PhysERI8, self).__init__(model, frozen=frozen)
symmetries = [
((0, 1, 2, 3), False),
((1, 0, 3, 2), False),
((2, 3, 0, 1), False),
((3, 2, 1, 0), False),
((2, 1, 0, 3), False),
((3, 0, 1, 2), False),
((0, 3, 2, 1), False),
((1, 2, 3, 0), False),
]
[docs]
def get_block_k_ix(eri, k):
"""
Retrieves k indexes of the block with a specific momentum transfer.
Args:
eri (TDDFTMatrixBlocks): ERI of the problem;
k (tuple, int): momentum transfer: either a pair of k-point indexes specifying the momentum transfer
vector or a single integer with the second index assuming the first index being zero;
Returns:
4 arrays: r1, r2, c1, c2 specifying k-indexes of the ERI matrix block.
+-----------------+-------------+-------------+-----+-----------------+-------------+-------------+-----+-----------------+
| | k34=0,c1[0] | k34=1,c1[1] | ... | k34=nk-1,c1[-1] | k34=0,c2[0] | k34=1,c2[1] | ... | k34=nk-1,c2[-1] |
+-----------------+-------------+-------------+-----+-----------------+-------------+-------------+-----+-----------------+
| k12=0,r1[0] | | |
+-----------------+ | |
| k12=1,r1[1] | | |
+-----------------+ Block r1, c1 | Block r1, c2 |
| ... | | |
+-----------------+ | |
| k12=nk-1,r1[-1] | | |
+-----------------+---------------------------------------------------+---------------------------------------------------+
| k12=0,r2[0] | | |
+-----------------+ | |
| k12=1,r2[1] | | |
+-----------------+ Block r2, c1 | Block r2, c2 |
| ... | | |
+-----------------+ | |
| k12=nk-1,r2[-1] | | |
+-----------------+---------------------------------------------------+---------------------------------------------------+
"""
# All checks here are for debugging purposes
if isinstance(k, int):
k = (0, k)
r1, c1 = eri.get_k_ix("knmj", k)
assert r1[k[0]] == k[1]
# knmj and kjmn share row indexes
_, c2 = eri.get_k_ix("kjmn", (0, r1[0]))
assert abs(r1 - _).max() == 0
# knmj and mnkj share column indexes
_, r2 = eri.get_k_ix("mnkj", (0, c1[0]))
assert abs(c1 - _).max() == 0
_r, _c = eri.get_k_ix("mjkn", (0, r2[0]))
assert abs(r2 - _r).max() == 0
assert abs(c2 - _c).max() == 0
_c, _r = eri.get_k_ix("mjkn", (0, c2[0]))
assert abs(r2 - _r).max() == 0
assert abs(c2 - _c).max() == 0
assert abs(r1 - c1).max() == 0
assert abs(r2 - c2).max() == 0
assert abs(r1[r2] - numpy.arange(len(r1))).max() == 0
# The output is, basically, r1, argsort(r1), r1, argsort(r1)
return r1, r2, c1, c2
[docs]
def vector_to_amplitudes(vectors, nocc, nmo):
"""
Transforms (reshapes) and normalizes vectors into amplitudes.
Args:
vectors (numpy.ndarray): raw eigenvectors to transform;
nocc (tuple): numbers of occupied orbitals;
nmo (int): the total number of orbitals per k-point;
Returns:
Amplitudes with the following shape: (# of roots, 2 (x or y), # of kpts, # of occupied orbitals,
# of virtual orbitals).
"""
if not all(i == nocc[0] for i in nocc):
raise NotImplementedError("Varying occupation numbers are not implemented yet")
nk = len(nocc)
nocc = nocc[0]
if not all(i == nmo[0] for i in nmo):
raise NotImplementedError("Varying AO spaces are not implemented yet")
nmo = nmo[0]
vectors = numpy.asanyarray(vectors)
vectors = vectors.reshape(2, nk, nocc, nmo-nocc, vectors.shape[1])
norm = (abs(vectors) ** 2).sum(axis=(1, 2, 3))
norm = 2 * (norm[0] - norm[1])
vectors /= norm ** .5
return vectors.transpose(4, 0, 1, 2, 3)
[docs]
class TDRHF(rhf_slow.TDRHF):
eri4 = PhysERI4
eri8 = PhysERI8
v2a = staticmethod(vector_to_amplitudes)
def __init__(self, mf, frozen=None):
"""
Performs TDHF calculation. Roots and eigenvectors are stored in `self.e`, `self.xy`.
Args:
mf (RHF): the base restricted Hartree-Fock model;
frozen (int, Iterable): the number of frozen valence orbitals or the list of frozen orbitals for all
k-points or multiple lists of frozen orbitals for each k-point;
"""
super(TDRHF, self).__init__(mf, frozen=frozen)
self.e = {}
self.xy = {}
[docs]
def kernel(self, k=None):
"""
Calculates eigenstates and eigenvalues of the TDHF problem.
Args:
k (tuple, int): momentum transfer: either an index specifying the momentum transfer or a list of such
indexes;
Returns:
Positive eigenvalues and eigenvectors.
"""
if k is None:
k = numpy.arange(len(self._scf.kpts))
if isinstance(k, int):
k = [k]
for kk in k:
self.e[kk], self.xy[kk] = self.__kernel__(k=kk)
return self.e, self.xy
