Input

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VASP basically gives 4 input files for standard production runs:

INCAR

• The INCAR file gives the input paramteres 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 fulfil your requirements concerning required precision, requested convergence, calculation time ...

POSCAR

• A sample POSCAR file can look as the following:

fcc:  Ni
3.53
0.5 0.5 0.0
0.0 0.5 0.5
0.5 0.0 0.5
Ni
1
Selective Dyn
Cartesian
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 (carthesian or direct).
  • 8-x: Positions of the atoms.

KPOINTS

• A sample KPOINTS file can look like the following:

Automatic mesh
0
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. $N_{\overrightarrow{k}} = 0$: automatic generation scheme.
  • 3: $\Gamma$-centered (Monkhorst-Pack) grid.
  • 4: Number of subdivisions in each direction.
  • 5: Optional shift of the mesh.

POTCAR

• 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 atoms, the atomic POTCAR files have to be concatenated, in the same order as the atoms are given in the POSCAR file.
• Different XC-types must not be mixed.

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