Version 1.2: Change log
Generates a suitably converged k-point grid for solid-state quantum chemical calculations.
Two programs are provided: kgrid and kgrid-series
From the command line
kgrid FILE -t TYPE -c CUTOFF
will return a suggested set of mesh dimensions. FILE can be any file format supported by ASE; if no FILE is specified, kgrid will look for a geometry.in file in the current directory. TYPE is a string specifying the format of this file; usually this argument can be left out and the correct type will be inferred by ASE. CUTOFF is the real-space cutoff parameter in Å and defaults to 10.0.
There is an internal Python function which may prove useful to ASE users, with the form
kgrid.calc_kpt_tuple(atoms, cutoff_length=10)
where atoms
is an ASE atoms object and the function returns a
tuple. As such, kgrid may be used while setting up a calculation
with a typical ASE calculator. For example:
import kgrid
from ase.io import read
from ase.calculators.vasp import Vasp
atoms = read('my_favourite_structure.cif')
calc = Vasp(xc='PBE',
kpts=kgrid.calc_kpt_tuple(atoms))
atoms.set_calculator(calc)
atoms.get_total_energy()
would perform a VASP calculation in the current directory with the PBE functional, using kgrid to determine the reciprocal-space sampling.
kgrid-series FILE -t TYPE --min MIN --max MAX
Example output:
Length cutoff KSPACING Samples
------------- -------- ------------
10.630 0.2956 2 7 4
11.260 0.2790 2 8 4
11.860 0.2649 2 8 5
12.148 0.2586 3 8 5
13.666 0.2299 3 9 5
14.075 0.2232 3 10 5
15.185 0.2069 3 10 6
16.703 0.1881 3 11 6
16.890 0.1860 3 12 6
17.790 0.1766 3 12 7
18.222 0.1724 4 12 7
19.705 0.1594 4 13 7
19.741 0.1591 4 13 8
21.259 0.1478 4 14 8
22.520 0.1395 4 15 8
22.777 0.1379 4 15 9
23.720 0.1324 4 16 9
24.296 0.1293 5 16 9
25.335 0.1240 5 17 9
25.814 0.1217 5 17 10
27.333 0.1149 5 18 10
28.150 0.1116 5 19 10
28.852 0.1089 5 19 11
29.650 0.1060 5 20 11
Use the --castep
option to replace KSPACING with "MP SPACING", which
corresponds to the KPOINTS_MP_SPACING parameter in CASTEP
(i.e. divide by 2π).
kgrid uses setuptools; from a reasonable healthy Python environment you can use
pip install .
with the usual pip caveats:
--user
flag is highly recommended and avoids the need for administrator privileges, but on a somewhat unhealthy Python installation the user packages location may not be on your paths yet.-e
flag creates an "editable" installation which links to this repository and enables easy updates with git.kgrid is not developed on Windows but no problems are anticipated; the Anaconda Python distribution includes pip. We have had good experiences using the Windows subsystem for Linux (WSL), available on Windows 10. On Mac OSX, the system Python does not include pip but there are various ways of getting a more complete distribution such as Homebrew or Anaconda.
To run the unit tests, install pytest
and pytest-mock
and run
pytest
from the project directory (i.e. the folder containing this
README.)
This program is not affiliated with ASE or any particular quantum chemistry code. This program is made available under the GNU General Public License; you are free to modify and use the code, but do so at your own risk.
[1] Moreno, J., & Soler, J. (1992). Optimal meshes for integrals in real- and reciprocal-space unit cells. Physical Review B, 45(24), 13891–13898. doi:10.1103/PhysRevB.45.13891