vasp-input-preparation

Overview

Use this skill to produce execution-ready VASP input trees without fighting tool-enforced defaults.

Quick Start

1. Choose vasp_relax_prepare for ionic relaxation and vasp_sp_prepare for static calculations.
2. Set calc_type correctly: bulk, slab, or gas.
3. Put one preparation campaign under one clean output_root.
4. Override INCAR only where the tool actually allows it.

Suggested tools

• vasp_relax_prepare
• vasp_sp_prepare

Workflow

1. Pick the right preparation tool

• vasp_relax_prepare is for relax jobs.
• vasp_sp_prepare is for static jobs and already enforces NSW=0, IBRION=-1.

2. Choose the correct regime

• bulk: periodic bulk models; relax_cell=True is allowed and switches ISIF=3.
• slab: surface slabs; ISIF=2, KPOINTS z forced to 1, relax_cell=True is invalid.
• gas: molecules or gas references; forced 1x1x1 KPOINTS and relax_cell=True is invalid.

3. Respect built-in defaults

• The tool already owns the main preset, including pseudopotential family, ENCUT, EDIFF, smearing defaults, and relax-vs-SP mode settings.
• compute_dos, use_d3, use_dft_plus_u, and enable_dipole are the toggles worth surfacing when they matter.
• Project house default for k_product is 35 for production slab work unless the task explicitly provides a convergence-backed value.

4. Override carefully

• user_incar_settings is for targeted overrides, not replacing the preset.
• MAGMOM, LDAUU, and LDAUJ must be element maps.
• null can remove optional keys, but tool-required regime keys still win.

5. Keep output layout clean

• Single structure input writes to output_root/<stem>/.
• Directory input preserves relative layout and appends <stem>/ per structure.
• Do not mix unrelated relax and SP campaigns in the same ambiguous tree.

Method-critical defaults

• Do not silently rely on defaults for use_d3, use_dft_plus_u, enable_dipole, spin treatment, or reference-state-sensitive INCAR toggles when they affect comparison.
• Keep clean slab, gas-phase reference, adsorbed structures, and downstream static calculations scientifically comparable.
• For slab adsorption studies, do not set relax_cell=true unless the task explicitly requires a variable-cell study and the system is not in slab mode.
• For slab work, use k*a ~= 35 Å as the initial project default unless convergence evidence justifies something else.
• Do not force bulk references to obey the slab default. Bulk k_product should be chosen from the bulk convergence requirement, not copied mechanically from slab policy.
• For DOS / projected-DOS / finer electronic-structure jobs, it is acceptable to increase k_product to around 50 when the extra sampling is part of the stated objective.
• Always report any non-default toggles that materially affect interpretation.

Output Contract

Return:

• output_root_rel
• representative prepared directory
• processed structure count
• any non-default method toggles or overrides that materially affect execution

References

• Inspect the tool schema/source when edge cases around k_product, DFT+U, or INCAR normalization matter.