ENCUTGWSOFT

From VASP Wiki

ENCUTGWSOFT = [real] 

Default: ENCUTGWSOFT = ENCUTGW for ALGO=ACFDT
= ENCUTGW as of VASP.6.3
= ENCUTGW else
Important: For vasp.6.3 and later releases ENCUTGWSOFT always defaults to ENCUTGW.

Descprition: The flag ENCUTGWSOFT sets the energy cutoff for response function, such that it allows to truncate the Coulomb kernel slowly between the energy specified by ENCUTGWSOFT and ENCUTGW using a cosine window function.


RPA/ACFDT correlation energies converge very slowly with respect to . Thus VASP automatically extrapolates to the infinite basis set limit using a linear regression to the equation: [1][2][3]

.

This usually leads to much smoother energy-volume curves in ACFDT calculations and MP2 calculations. The modified Coulomb kernel is in this case:

If LSCK is set to .TRUE., the squeezed Coulomb kernel is used instead of the cosine window:[4]

This kernel squeezes contributions from large wave vectors into the window given by ENCUTGWSOFT.

Mind: The infinite basis set limit extrapolation for RPA/ACFDT is described in more detail here.

Related tags and articles

PRECFOCK, ENCUT, ENCUTGW, GW calculations, LSCK, RPA/ACFDT basis set convergence, Examples that use this tag