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13.3 Default energy cutoff

 

The PSEUDO and POTCAR files generated by rhfsps and fourpot3 contain a default energy cutoff, which might be used for the calculations with VASP. The default cutoff guarantees reliable calculations, with errors in the eigenvalues smaller than 1 mRy (i.e. 13 meV, for s-elements the error is usually much smaller). This is sufficient as long as the stress tensor is not important, because Pulay contributions are usually not negligible for this cutoff. (increase the cutoff by a factor of 1.5 if Pulay contributions should be avoided).

The default energy cutoff works only for US-PP constructed with the RRKJ scheme. The default cutoff is proportional to the square of the highest expansion coefficient used in the RRKJ scheme[16, 40].

( tex2html_wrap_inline5187 is in a.u., whereas ENMAX is in eV, therefore the conversion factor 13.6058). There is also a line ENMIN in the POTCAR and PSEUDO file, ENMIN corresponds to the minimal energy required for a reasonable accurate calculation (for instance ENMIN is sufficient for molecular dynamics), ENMIN is calculated according to

( tex2html_wrap_inline5187 is in a.u., whereas ENMIN is in eV, therefore the conversion factor 13.6058).



MASTER USER VASP
Mon Mar 29 10:38:29 MEST 1999