ecuts variable

NAME

  ecuts -confinement operator cutoff

DESCRIPTION

The ecuts variable enters the expression of the confinement operator which is added to the Kohn-Sham hamiltonian when computing the stress tensor (when stress is set to ON). The confinement operator is diagonal in the plane wave basis and ensures that the resolution used for the description of the wavefunctions is independent of cell size.

H_conf(G) = facs * 0.5 * G2 * (1 - f((0.5*G2 - ecuts)/sigmas))

f(E) = 1 / ( 1 + exp(E) )
 

The effect of the confinement operator is to reduce the amplitude of the wavefunctions' Fourier coefficients for large wave vectors (G2 > ecuts)

DEFAULT VALUE

0

ALLOWED VALUES

[0,ecut]

RELATED INFORMATION

stress, facs, sigmas, refcell,


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