liminfoVASP Reference
Free reference guide: VASP Reference
About VASP Reference
The VASP Reference is a specialized quick-reference guide for the Vienna Ab initio Simulation Package, covering all essential INCAR parameters, POSCAR coordinate formats, KPOINTS grid configurations, POTCAR pseudopotential selection, and output analysis settings used in density functional theory (DFT) calculations.
This reference organizes 28 key VASP parameters across seven categories: INCAR Basics (ENCUT, PREC, EDIFF, ISMEAR, NCORE), INCAR Ionic (IBRION, NSW, ISIF for structure optimization), INCAR Electronic (ISPIN, ALGO, LREAL, GGA, IVDW, LDAU for exchange-correlation and DFT+U), POSCAR (Direct vs Cartesian coordinates, Selective dynamics), KPOINTS (Gamma-centered, Monkhorst-Pack, band structure k-paths), Input Files (POTCAR types), and Analysis (LORBIT, NEDOS, LWAVE/LCHARG output control).
Whether you are running a single-point energy calculation, optimizing a crystal structure with variable cell shape, computing band structures, or setting up DFT+U corrections for strongly correlated transition metal oxides, this reference provides the exact INCAR tags and recommended values. All content is accessible instantly in your browser without any installation.
Key Features
- Complete INCAR parameter reference covering ENCUT, PREC, EDIFF, EDIFFG, ISMEAR, SIGMA, and parallelization settings
- Ionic relaxation tags including IBRION algorithms (CG, RMM-DIIS, finite difference), NSW step counts, and ISIF stress tensor control
- Electronic structure parameters for ISPIN, ALGO minimization methods, LREAL projection, GGA functionals (PBE, PBEsol, SCAN), and IVDW dispersion corrections
- DFT+U setup guide with LDAU, LDAUTYPE, LDAUL, LDAUU, and LDAUJ for strongly correlated d/f orbital systems
- POSCAR format reference with Direct vs Cartesian coordinates and Selective dynamics for surface slab calculations
- KPOINTS configuration for Gamma-centered grids, Monkhorst-Pack meshes, and Line-mode band structure k-paths
- Analysis output control with LORBIT projected DOS, NEDOS resolution, and LWAVE/LCHARG file management
- Bilingual Korean and English entries with recommended values and convergence test guidelines for each parameter
Frequently Asked Questions
What VASP input files does this reference cover?
This reference covers all four main VASP input files: INCAR (calculation parameters like ENCUT, ISMEAR, IBRION, ALGO), POSCAR (atomic positions in Direct or Cartesian format with optional Selective dynamics), KPOINTS (Gamma, Monkhorst-Pack, and band structure line-mode), and POTCAR (PAW pseudopotential selection including _sv and _GW variants).
How do I choose the right ENCUT value?
ENCUT sets the plane-wave energy cutoff in eV. The recommended practice is to use 1.3 times the ENMAX value from your POTCAR file. A convergence test is essential: increase ENCUT until total energy changes by less than 1 meV/atom. Common values range from 400-600 eV depending on the elements involved.
What is the difference between ISMEAR 0 and ISMEAR 1?
ISMEAR=0 uses Gaussian smearing, recommended for semiconductors and insulators with a small SIGMA (0.05 eV). ISMEAR=1 uses first-order Methfessel-Paxton smearing, preferred for metals. For accurate DOS and total energy calculations, ISMEAR=-5 (tetrahedron method with Blochl corrections) is recommended with sufficient k-points.
How do I set up a structure optimization in VASP?
For structure optimization, set IBRION=2 (conjugate gradient) for initial relaxation or IBRION=1 (RMM-DIIS) near equilibrium. Set NSW=100-300 for maximum steps, EDIFFG=-0.02 for force convergence (negative value = force criterion in eV/A), and ISIF=2 for fixed cell or ISIF=3 for full cell relaxation including volume.
How do I compute a band structure with VASP?
Band structure calculation requires two steps: first, a self-consistent calculation with a regular k-grid to generate CHGCAR. Then, a non-self-consistent calculation (ICHARG=11) using KPOINTS in Line-mode with high-symmetry k-path points. Set LORBIT=11 for projected band character analysis.
What GGA functional options are available?
The GGA tag selects the exchange-correlation functional: PE for PBE (default, general purpose), PS for PBEsol (better for solid lattice constants), RP for revPBE. For meta-GGA SCAN, set METAGGA=SCAN. Van der Waals corrections can be added with IVDW=11 (DFT-D3) or IVDW=12 (DFT-D3 with BJ damping).
How do I set up DFT+U in VASP?
Set LDAU=.TRUE., LDAUTYPE=2 (Dudarev approach), then specify LDAUL (angular momentum: 2 for d-orbitals, 3 for f-orbitals), LDAUU (Hubbard U values in eV), and LDAUJ (exchange J values). The effective U is Ueff = U - J. Common values are U=3-5 eV for transition metal d-orbitals.
What parallelization settings should I use?
Set NCORE to the number of cores per band (typically 4-8 for most systems). For k-point parallel calculations, use KPAR to divide k-points across node groups. The optimal setting depends on your system size and cluster architecture. NCORE * KPAR should not exceed your total core count.