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Next: 7.30 NELECT Up: 7 The INCAR File Previous: 7.28 NPACO and APACO-tag

7.29 POMASS, ZVAL, RWIGS-tag

 

These three lines determine the valence and the atomic mass and the Wigner Seitz radius for each atomic species. These lines are mainly to assure compatibility between the POTCAR file and the INCAR file. The POTCAR file also contains valence information, the ordering in the POTCAR file must be the same as in the INCAR file and POSCAR file. If incompatibilities exist VASP will stop.

The Wigner Seitz radius is optional, if it is supplied, partial spd-wavefunction characters and the local partial DOS and are evaluated (see section 5.16). For mono-atomic system RWIGS can be defined unambiguously. The sum of the volume of the spheres around all atoms must be the same as the total volume of the cell (assuming that you do not have a vacuum region within your cell). VASP will write a line

 Volume of Typ   1:     98.5 %
to the OUTCAR file. You should use an RWIGS which gives approximately tex2html_wrap_inline4631 .

For binary system there is no unambiguous way to define RWIGS. Several choices are possible, but in all cases the sum of the volumes of the spheres around all atoms must be close to the total volume of the cell (i.e the sum of the values given by VASP should be tex2html_wrap_inline4631 ).

Whatever you chose, you should know that results are always qualitative i.e. there is no unambiguous way to determine the location of an electron (you can for instance hardly say anything about the charge transfer). What you can learn from the partial DOS is the typical character of a peak in a DOS, quantitative results can be obtained only be choosing a reference system and making comparison with this reference system (e.g. bulk versus surface, or bulk versus liquid system).


next up previous contents
Next: 7.30 NELECT Up: 7 The INCAR File Previous: 7.28 NPACO and APACO-tag

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