[Pw_forum] dosup and pdosup in pdos_tot file

[Gabriele Sclauzero]

Dear Koa (please specify your affiliation),


On 09/22/2010 11:01 PM, B. Koa wrote:
>
>    Dear PWScf Users and Gabriele
>
>    As I have read in the tutorial_magn.pdf which prepared by Paolo 
> Giannozzi they are too close to each other but not exactly the same as 
> each other and I don't understand the meaning of dosup and pdosup in 
> the pdos_tot file well; but generally I know the definition of DOS and 
> PDOS.

So it should be easy for you to understand: dosup is the DOS for up-spin 
states, while pdosup is the PDOS for up-spin states. Since you know the 
definitions of DOS and PDOS, you must be able to understand why they are 
not the same and why they can be almost equal in some energy range (the 
agreement is usually better at lower energies).


> Also some values of dosup and pdosup in the pdos_tot file have 
> negative sign ! (at higher energies ) but there are not such negative 
> sign of dosup in the *.dos file. What do the negative values mean?

Negative values in the PDOS (and in the DOS as well) may appear if you 
have used a smearing function like the Methfessel-Paxton one. For 
plotting the DOS it is usually more convenient to adopt the gaussian 
smearing (ngauss=0), even if you used a different one in the scf/nscf 
calculations. For computing DOS integrals, instead, you should use the same.


HTH

GS


>
>   Truly Yours
>   Koa
>
>       me :
>     > Dear PWScf Users
>     >
>     > It seems that "dosup" and "pdosup" which are in the pdos_tot
>     file must
>     > be equal and really they are equal in many cases. But in some cases
>     > they differ a very bit with each other. I think that the origin of
>     > this very small difference is only the numerical procedure and
>     not any
>     > physical one. Am I correct ?
>
>     Gabriele :
>
>     I don't think your statement is correct. DOS (density of states) and
>     PDOS (projected DOS) are not the same quantity (otherwise why
>     should one
>     give them distinct names?). Please spend some time in searching their
>     respective definitions (on textbooks, in the forum archives, or even
>     looking at the code itself).
>
>
>
>
>
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>    


-- 

Gabriele Sclauzero, EPFL SB ITP CSEA
PH H2 462, Station 3, CH-1015 Lausanne

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