Target periodic system#
In this section, you can set up the system with spatially periodic boundary condition subject to calculation. This setting is exclusive to the target molecule setting. For periodic systems, the density-fitting approximation is always valid.
Geometry#
You can specify a molecular structure to be calculated in either Cartesian coordinates or in Z-matrix notation. An error occurs if not specified.
Atoms#
Enter a list of nuclei that make up the target system.
Coordinates#
Specify a structure in a cell with a list of coordinates of the nuclei
in the same order as in the list of nuclei atoms
. The coordinates of
the molecule should be specified in Å units.
Dimension#
Specify the number of dimensions with periodicity. The default value is 3.
Translation Vector#
Enter a list of translation vectors that characterize a periodic
boundary condition with trans_vector
key.
Grid of K-points#
Enter a list of the number of k points for each axis of the reciprocal
space with kpt_grid_shape
key.
Basis set#
You can set up basis functions, which are supported by PySCF. An error occurs if not specified.
Multiplicity#
Value of the spin multiplicity \(2S+1\) of the target state. An error occurs if not specified or found to be inconsistent with the given number of electrons.
Number of excited states#
Number of excited states subject to calculation (Default: 0)
Complete active space#
You can specify a complete active space cas
by setting number of
orbitals and number of electrons in the active space.
active_orb
: Number of orbitals in the active space.active_ele
: Number of electrons in the active space.cas_list
: Ordered list of orbtal indices (0-origin) in the active space. If no input is given, the active orbitals will be chosen from around HOMO, LUMO.
You can set different cas
for different k with cas_for_each_k
key.
It must be given by the list of cas
.
Scaled center#
Shift the k-points to be centered on scaled_center, which is specified as the coefficients of the raciprocal lattice vector. For each element, the value must be a number between -1 and 1.
Cartesian basis functions#
The basis functions used by PySCF can be specified in Cartesian coordinates for the d and f orbitals (6d, 10f), rather than the irreducible representation of \(S_z\) eigenstates (5d, 7f).
cart_basis
: set to true to use Cartesian basis functions (Default: false)
Effective core potentials#
The effective core potentials passed to PySCF can be specified as a list of dicts.
ecp
: a list of dicts, each corresponding to one atom. For each atom set theatom
field and thebasis
fields.atom
: atomic species, i.e."Na"
,"Cu"
, etc.basis
: basis to represent it in, i.e."crenbs"
,"lanl2dz"
, etc.
Atom specific basis#
The basis set used by PySCF can be specified for each atom as a list of dicts (similar to effective core potentials).
This field cannot be set if basis
is set.
atom_specific_basis
: a list of dicts, each corresponding to one atom. For each atom set theatom
field and thebasis
fields.atom
: atomic species, i.e."Na"
,"Cu"
, etc.basis
: basis to represent it in, i.e."sto-3g"
,"6311++g**"
, etc.
Input example#
"target_periodic_system": {
"geometry": {
"atoms": ["H", "H"],
"coordinates": [
[
[0, 0, 0],
[1.42, 0, 0]
]
],
"dimension": 3,
"trans_vector": [
[2.13, -1.2297560733739028, 0],
[2.13, 1.2297560733739028, 0],
[0, 0, 5]
],
"kpt_grid_shape": [2, 1, 1]
},
"basis": "sto-3g",
"num_excited_states": 0,
"cas": {
"active_ele": 2,
"active_orb": 2
},
"multiplicity": 1,
"cart_basis": false
}