The following flags control the behaviour of VASP:
LEFG
-tag (default: .FALSE.
)
LEFG = .TRUE. | .FALSE.
LEFG
switches on the calculation of the electric field gradient tensors. The EFG tensors
are symmetric. The principal components
Beware: Attaining convergence can require somewhat smaller EDIFF
than the default of 1.e-4
and somewhat larger cutoff ENCUT
than default with PREC=A
. Moreover, the calculation of
EFGs typically requires high quality PAW data sets. Semi-core electrons can be important (check with
*_pv
or *_sv
POTCARs) as well as explicit inclusion of augmentation channel(s) with -projectors.
QUAD_EFG
-tag (default: 1.) This tag allows the conversion by VASP of the
QUAD_EFG
-tag consists of the nuclear quadrupole moment in millibarns for each atomic species, in the same
order as in the POTCAR file. The output
Suppose a solid contains Al, C and Si, than the QUAD_EFG
-tag could read:
QUAD_EFG = 146.6 33.27 0
Beware: several definitions of are used in the NMR community.
Beware: for heavy nuclei inaccuracies are to be expected because of an incomplete treatement of relativistic effects.