Pre-processing¶

Valyte provides three pre-processing utilities for setting up VASP calculations — supercell generation, interactive k-point grids, and automatic POTCAR generation.

Band structure k-paths

For line-mode KPOINTS (band structure calculations), see valyte band kpt-gen instead.

Supercell¶

Generate a supercell from a POSCAR file.

valyte supercell nx ny nz [options]

Option	Default	Description
`-i`, `--input`	`POSCAR`	Input POSCAR file
`-o`, `--output`	`POSCAR_supercell`	Output filename

# 2×2×2 supercell
valyte supercell 2 2 2

# 3×3×1 slab supercell with custom filenames
valyte supercell 3 3 1 -i POSCAR_primitive -o POSCAR_3x3x1

K-Points — Interactive SCF grid¶

Generate a KPOINTS file for SCF or relaxation calculations interactively.

valyte kpt

The command will prompt for:

K-mesh scheme — Monkhorst-Pack or Gamma
K-spacing — in units of 2π/Å (e.g. 0.04)

The optimal k-grid dimensions are automatically calculated from the lattice vectors in your POSCAR.

Tip

A k-spacing of 0.03–0.05 (2π/Å) is typical for DFT calculations. Use smaller values (denser grids) for metals or accurate total energy convergence.

POTCAR¶

Generate a POTCAR file from the species listed in your POSCAR.

valyte potcar [options]

Option	Default	Description
`-i`, `--input`	`POSCAR`	Input POSCAR file
`-o`, `--output`	`POTCAR`	Output filename
`--functional`	`PBE`	Pseudopotential functional

Available functionals: PBE, PBE_52, PBE_54, LDA, LDA_52, LDA_54, PW91, and others supported by Pymatgen.

# Default PBE
valyte potcar

# Use PBE_54
valyte potcar --functional PBE_54

# Custom input and output
valyte potcar -i POSCAR_relaxed -o POTCAR_new

Pymatgen configuration required

This command uses Pymatgen to locate your VASP pseudopotential files. You must set PMG_VASP_PSP_DIR in ~/.pmgrc.yaml to point to the directory containing your PAW potentials.

PMG_VASP_PSP_DIR: /path/to/your/pseudopotentials

See the pymatgen documentation for full setup instructions, or the FAQ → POTCAR errors for troubleshooting.