ENCUT-tag

ENCUT = kinetic energy cutoff

default taken from POTCAR-file

Cut-off energy for plane wave basis set in eV. All plane-waves with a kinetic-energy smaller than $E_ {\rm cut}$ are included in the basis set: i.e.

$$\vert {\bf G}+ {\bf k}\vert < G_{\rm cut} \qquad \mbox{with} \qquad E_{\rm cut}=\frac{\hbar^2}{2m}G_{\rm cut}^2$$

The number of plane waves differs for each k-point, leading to a superior beahviour for e.g. energy-volume calculations. If the volume is increased the total number of plane waves changes fairly smoothly. The criterion $\vert {\bf G}\vert < G_{\rm cut}$ (i.e. same basis set for each k-point) would lead to a very rough energy-volume curve and, generally, slower energy convergence.

Starting from version VASP 3.2 the POTCAR files contains a default ENMAX (and ENMIN) line, therefore it is in principle not necessary to specify ENCUT in the INCAR file. For calculations with more than one species, the maximum cutoff ( ENMAX or ENMIN) value is used for the calculation (see below, Sec. 6.10). For consistency reasons we still recommend to specify the cutoff manually in the INCAR file and keep in constant throughout a set of calculations.