k_space grid parameters

The parameters here are for generating Fourier space numerical grids.


keyword: calculation.k_spacegrids.number

possible values: 3 x 1 integer array

default value: determined by the value of k_spacegrids.L_cutoff

description: number of small k-space grids in each direction. It is used to divide the Brillouin zone into the input number of small grids.

an example:

calculation.k_spacegrids.number = [8 8 8]'


keyword: calculation.k_spacegrids.L_cutoff

possible values: a double number with proper length unit such as ‘au’, ‘a.u.’, ‘atomic unit’, ‘Bohr’ ‘an’, ‘ang’, ‘angstrom’, ‘nm’, ‘nanometer’, where ‘au’ ‘a.u.’, and ‘atomic unit’ are for Bohr, ‘an’ and ‘ang’ for angstrom, and ‘nm’ for nanometer.

default value: 20, 40, or 80 Bohr, depending on the value of the parameter calculation.control.precision.

description: the equivalent length cut-off of the k-space grid density. k-space grid length ~ (pi/L_cutoff). The input parameter will not be used when k_spacegrids.number is given. Note that if the number part of the input is missing, it will be considered as 1, and if the unit part is missing, it will be considered to use the unit defined by calculation.control.lengthUnit.

an example:

calculation.k_spacegrids.L_cutoff = 40


keyword: calculation.k_spacegrids.shift

possible values: 3 x 1 or 1 x 3 array, [s_1, s_2, s_3], with each s_i a double number between 0 and 1.

default value: [0 0 0]’

description: k-space grid point shift. While all s_i are set to be 0, the Gamma point is always among the k-space grid points being generated; otherwise, the k-space grid points will be shifted s_1, s_2, and s_3 grid length along their grid vector directions, respectively.

an example:

calculation.k_spacegrids.shift = [1/2 1/2 1/2]'


keyword: calculation.charge.indexProjected

possible values: cell array of n\(\times\)1 integer array

default value: all ells, orbitals, atoms, or grids

description: If whatProjected is Ell, Orbital, or Atom, each cell contains a set of ell values of angular momentum, or a set of atoms or orbitals. If whatProjected is Grid, the length of the cell array must be three, and each cell is a set of grid numbers along corresponding direction. For example,if indexProjected = {[3,4], [5], [6,7,8]}, the number of electrons will be calculated in the 2*1*3 = 6 grids of (3,5,6), (3,5,7), (3,5,8), (4,5,6), (4,5,7), and (4,5,8). This parameter is not used when whatProjected is None. Please note that the order of the atoms and orbitals has been listed in the output file Atoms.txt, which can be used to identify the orbital or atom index.

an example:

calculation.charge.indexProjected = {0 1 2}


keyword: calculation.realspacegrids.clusterfactor

possible values: an integer number

default value: 5

description: Defines the number of grid points in each direction which are grouped into a cluster for saving index storage on the grids.

an example:

calculation.realspacegrids.clusterfactor = 5