[Pw_forum] local DOS: how to set nrmin and nrmax

[Guido Fratesi]

Dear Jinxi,

the definition of irmin and irmax depends on your choice of the volume 
where the local DOS has to be integrated. Reasonable numbers go from 1 
(first point in the FFT grid) to N (last point in the FFT grid) where N 
is output by pw.x (see "FFT grid:"). Points in real space going from 
irmin to irmax are included. This is done for the three dimensions 
independently. So suppose you want to take a volume which goes from the 
origin of the unit cell to half of it in the three dimensions (12.5% of 
total volume), and your FFT grid contains 64x64x50 points, then you 
would set:
irmin(1)=1
irmax(1)=32
irmin(2)=1
irmax(2)=32
irmin(3)=1
irmax(3)=25

HTH
Guido

PS:
Unless for specialized applications, you might perhaps be interested in 
the "projected" (on the atomic wavefunctions) rather than "local" DOS, 
both are computed by projwfc.x.


Il 12/06/2011 10:17 AM, jinxi ha scritto:
> Dear all:
> I try to get local DOS using projwfc.x, but i can't understand the
> description in "INPUT_projwfc": how to set parameters irmin and irmax?
> I've read the input files in example16, but i still don't know how to
> locate the local DOS by irmin and irmax. Are there general methods to
> calculate the number and position of grid points?
> If there are some general references (books, articles, presentations)
> for the basic knowledge, please recommend to me.
> Many thanks!
> best wishes
> jinxi
>
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum

-- 
Guido Fratesi

Dipartimento di Scienza dei Materiali
Universita` degli Studi di Milano-Bicocca