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Default: ADDGRID = .FALSE. 

Description: ADDGRID determines whether an additional support grid is used for the evaluation of the augmentation charges.

When ADDGRID=.TRUE. VASP uses an additional support grid for the evaluation of the augmentation charges. This grid contains 8 times more points than the standard "fine" grid (NGXF×NGYF×NGZF). Whenever terms involving augmentation charges are evaluated, this additional grid is used. For instance: The augmentation charge is evaluated first in real space on this additional grid, FFT-transformed to reciprocal space and then added to the total charge density on the standard "fine" grid (NGXF×NGYF×NGZF). The additional grid helps to reduce the noise in the forces significantly. In many cases, it even allows to perform calculations in which NGXF=NGX etc. The latter can be achieved by setting:


in the INCAR file. The flag can also be used for US-PPs, in particular, to reduce the noise in the forces.

Examples that use this tag