Input and Output - a short Intro

From VASP Wiki


VASP basically needs 4 input files for standard production runs:


The INCAR file holds the input parameters which "steer" the calculation.

  • The default values set by VASP itself are a clever choice to do standard calculations.
  • These standard settings can be modified to specify:
    • What do you want to do? (scf calculation, DOS, dielectric properties ...)
    • You can give parameters to fulfill your requirements concerning required precision, requested convergence, calculation time ...


The POSCAR file contains the information on the structure.

  • A simple POSCAR file may look like this:
fcc:  Ni
0.5 0.5 0.0
0.0 0.5 0.5
0.5 0.0 0.5
Selective Dyn
0 0 0  T T T
  • The description of each line is given as follows:
    • 1: Header (comment).
    • 2: Overall scaling constant.
    • 3-6: Bravais matrix.
    • 4: Name(s) of the atom(s).
    • 5: Number of the atoms (of each atom type).
    • 6: (optional: selective dynamics).
    • 7: Specifies which coordinate system is used ("cartesian" or "direct").
    • 8-x: Positions of the atoms.


The KPOINTS file determines the sampling of the 1st Brillouin zone.

Automatic mesh
G (M)
4 4 4
0.  0.  0.
  • The description of each line is given as follows:
    • 1: Header (comment).
    • 2: Specifies the k mesh generation type. : automatic generation scheme.
    • 3: -centered (Monkhorst-Pack) grid.
    • 4: Number of subdivisions in each direction.
    • 5: Optional shift of the mesh.


The POTCAR file contains the relevant information concerning the pseudo potentials that are necessary to run the calculation:

  • Data that was required for generating the pseudo potentials.
  • Number of valence electrons.
  • Atomic mass.
  • Energy cut-off.

If the cell contains different atomic species, the corresponding POTCAR files have to be concatenated, in the same order as the atomic species are given in the POSCAR file.

N.B.: Different XC-types must not be mixed.


VASP gives several different output files, depending on which task is performed. The most important files that are produced in (almost) every calculation are described in the following:


The OUTCAR file gives detailed output of a VASP run, including:

  • A summary of the used input parameters.
  • Information about the electronic steps: , KS-eigenvalues.
  • Stress tensors.
  • Forces on the atoms.
  • Local charges and magnetic moments.
  • Dielectric properties

The amount of output written onto the OUTCAR file can be chosen by modifying the NWRITE tag in the INCAR file.

OSZICAR and stdout

The OSZICAR file gives a short summary of the results:

  • Chosen SCF algorithm.
  • Convergence of the total energy, charge- and spin densities.
  • Free energies.
  • Magnetic moments of the cell.


The CONTCAR file gives the updated geometry data at the end of a run:

  • Lattice parameter.
  • Bravais matrix.
  • Ionic positions.
  • (Optionally velocities).

The format of the CONTCAR file is the same as of the POSCAR file, hence it can be used directly for continuation runs after having been copied to the POSCAR file.


The XDATCAR file contains updated ionic positions of each ionic step.


The DOSCAR file contains the total and integrated DOS and optionally the local partial DOS.


The CHGCAR file contains the charges .


The WAVECAR file contains the wave function coefficients. This file can be used to continue from a previous run.

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