PREC

PREC = Low | Medium | High | Normal | Single | Accurate 

Default: PREC	= Medium	for VASP.4.X
	= Normal	for VASP.5.X

Description: PREC specifies the "precision"-mode.

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Changing the PREC parameter influences the defaults for four sets of parameters (ENCUT; NGX, NGY, NGZ; NGXF, NGYF, NGZF, and ROPT):

PREC	NGX,Y,Z	NGXF,YF,ZF	ROPT
Normal	3/2×Gcut	2×NGX	-5×10-4
Single	3/2×Gcut	NGX	-5×10-4
Accurate	2×Gcut	2×NGX	-2.5×10-4
Low	3/2×Gcut	3×Gaug	-1×10-2
Medium	3/2×Gcut	4×Gaug	-2×10-3
High	2×Gcut	16/3×Gaug	-4×10-4

where

$E_{\rm {cut}}={\frac {\hbar ^{2}}{2m_{e}}}G_{\rm {cut}}^{2}\qquad E_{\rm {aug}}={\frac {\hbar ^{2}}{2m_{e}}}G_{\rm {aug}}^{2}$

with E_cut=ENCUT and E_aug=ENAUG.

Mind: the settings PREC=Normal and PREC=Accurate are only available in VASP.4.5 and newer versions. The setting PREC=Single is only available as of VASP.5.1.

Related Tags and Sections

NGX, NGY, NGZ, NGXF, NGYF, NGZF, ENCUT, ENAUG, ENMAX

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