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question on PDOS analysis

Posted: Mon Feb 15, 2010 3:29 am
by luke419
1. I'd like to know how can I obtain PDOS for each atom of material.
Should merely the following keywords be sufficient for it?

--------------------------------------------------
the description for RWIGS
NPAR=1
--------------------------------------------------


If it is not, would you let me know what I should write in INCAR to obtain PDOS result in detail and what contents in output files denote data for PDOS,please?


2. It seems that LDOS (DOS to each orbitals?) and PDOS (DOS to each atoms?) are different.
Is it right?

I've heard that existence of LORBIT should give the result for LDOS.
Then, what should I do for PDOS?
Does the exixtence of RWIGS give the result for PDOS?

I've seen that RWIGS is not required when PAW is used.
Is it right?
Then, should "the use of PAW and NPAR=1" give PDOS result "without RWIGS keyword and explicit assignment for them"?

3. In the case that RWIGS is required, with what criterion should they be assigned to each atoms in detail? Is it troublesome?
Can't they be assigned automatically by default?


With best regards,


Sincerely
Luke

question on PDOS analysis

Posted: Tue Feb 16, 2010 3:41 pm
by physicalattraction
I don't know exactly what you mean in VASP with LDOS, is it the local density of states, or in other words: the density of states as a function of spatial position?
PDOS is the density of states, projected onto the atoms. To know which parts in space belong to which atom, in general a Wigner-Seitz radius is required, this is the RWIGS flag. This can be different for every atom, the manual states a little bit about how to set them, but bear in mind that this radius is rather arbitrary. You calculate the site-projected DOS by setting the proper LORBIT flag.
If you use PAW POTCAR-files, you can set LORBIT to 11. This would result in a PROCAR file in which the density of states is splitted out for every atom for every orbital, so you can for instance plot the density of states of atom number 3 with p_x character or the density of states of atom number 12 with d_xy character, etc.
I don't know what the NPAR-flag has to do with this, this would set the number of cores used. The manual states: In vasp.4.6 the site projected DOS can be evaluated for LORBIT=10-12, even if NPAR is not equal 1 (contrary to previous releases).

So in short: if you use PAW POTCAR-files, set LORBIT = 11 and check the PROCAR file in the end.