KPOINTS

KPOINTS is a plain text input file used by many electronic structure and density functional theory (DFT) codes to specify how the Brillouin zone should be sampled in reciprocal space. It mainly governs the selection and arrangement of k-points used to integrate properties over the electronic structure. While the name and exact syntax are most closely associated with VASP, similar concepts appear in other packages, sometimes under different file names or input formats.

A KPOINTS file describes the type of k-point sampling, the grid or path to be used, and optionally the weights of individual k-points. Common modes include automatic (or Monkhorst-Pack) grids, gamma-centered grids, line-mode paths for band structure calculations, and explicit lists of k-points. In automatic and Monkhorst-Pack modes, a three-dimensional grid is specified by integer divisions along the a, b, and c directions, often with an optional shift vector to set the grid relative to the reciprocal lattice. The line-mode is used to sample along a high-symmetry path through the Brillouin zone, useful for plotting band structure. In explicit mode, a user provides a list of specific k-points and their weights.

The content of a KPOINTS file typically includes a header line describing the mode, a label line, a line with grid dimensions or the number of k-points, and subsequent lines listing k-point coordinates (and weights in explicit mode). The choice of k-point sampling affects convergence and computational cost; metals usually require denser grids than insulators for accurate energies and properties. Although KPOINTS is a VASP convention, the underlying idea—sampling reciprocal space to converge integrals—appears across many codes, where the equivalent input controls how finely the Brillouin zone is sampled.