ENCUT = [real]
|= largest ENMAX in the POTCAR file
Description: ENCUT specifies the energy cutoff for the plane-wave basis set in eV.
All plane waves with a kinetic energy smaller than are included in the basis set, i.e.,
With this energy cutoff, the number of plane waves included in the basis set depends on the k-point, leading to a superior behavior. For instance, for energy-volume calculations the total number of plane waves changes fairly smoothly according to the volume, while the criterion (i.e. same number of plane waves for all k-points) would lead to a very rough energy-volume curve and, generally, to a slower energy convergence with respect to the basis set size.
The POTCAR files contain a default ENMAX (and ENMIN). 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 PREC).