K-points Tools#

Calculate systematic k-point grids for DFT calculations.

kpoints - Calculate K-point Series#

Generate a series of k-point grids for convergence testing.

Usage#

matchest kpoints [FILENAME] [OPTIONS]

Options#

  • --min FLOAT - Minimum real-space cutoff in Å (default: 10)

  • --max FLOAT - Maximum real-space cutoff in Å (default: 30)

  • --comma-sep - Output as comma-separated list

  • --vasp - Use VASP KSPACING format (1/Å) instead of CASTEP MP_SPACING (2π/Å)

  • --realspace - Use real-space lattice lengths instead of reciprocal

Examples#

# CASTEP format (MP SPACING in 2π/Å)
matchest kpoints POSCAR --min 10 --max 30

# VASP format (KSPACING in 1/Å)
matchest kpoints POSCAR --vasp --min 10 --max 30

# Comma-separated for scripting
matchest kpoints POSCAR --comma-sep

Output#

Standard format (CASTEP):

Length cutoff (Å)  MP SPACING (2π/Å)    Samples
-----------------  -------------------  ------------
          10.000            0.050000     2   2   2
          15.000            0.033333     3   3   3
...

Comma-separated:

2 2 2,3 3 2,3 3 3,4 4 3,...

Background#

K-point grids are critical for DFT convergence. This tool:

  • Generates systematic series based on real-space cutoffs

  • Accounts for crystal symmetry to find unique grids

  • Supports both CASTEP (2π/Å) and VASP (1/Å) conventions