[Pw_forum] (really silly) questions about DOS calculations
Stefano de Gironcoli
degironc at sissa.it
Wed Jan 26 09:27:27 CET 2005
Dear Eduardo Ariel Menendez
Please notice that Fermi-Dirac approximation to delta function is
obtained with nagauss=-99 (minus 99 )
If you specify ngauss=+99 you get a very wierd function which is a
gaussian multiplied by some Hermite polynomial of degree 99*2 wildly
oscillating with 99*2-1 zeros within a few degauss around the fermi
energy ...
We should disable use of degauss larger than 1 (or maybe 2).... and
repalce ngauss in input with some more mnemonic definition as it is done
in pw.x
best regards,
Stefano de Gironcoli
Eduardo Ariel Menendez P wrote:
>Thank you very much, Paolo.
>
>The problem is only with dos.x, and it arises with this input
>
>&inputpp
> outdir='/home/emenendez/MyPWSCF/Ti3SiC2/DOS/',
> prefix='tisic',
> fildos='tisic.dos',
> ngauss=99,
> degauss=0.01,
> Emin=0, Emax=25.0, DeltaE=0.1
>/
>
>If ngauss is set to 0,1 or -1, the DOS is calculated. The problem is
>independent of the options used for the nscf calculation (occupation,
>smearing,degauss)
>
>Best regards
>Eduardo
>
>
>>On Sunday 23 January 2005 04:44, Eduardo Ariel Menendez P wrote:
>>
>>
>>
>>>2) Can one use occupations='smearing'+degauss+smearing='fermi-dirac'
>>>for a DOS calculation? if yes, has someone met the '1.0E+193' problem?
>>>
>>>
>>I never tried with fermi-dirac smearing, but it used to work with
>>simple gaussian smearing. Does the problem occur only with
>>fermi-dirac smearing or also with other kinds of smearing (simple
>>gaussian for instance)?
>>
>>Paolo
>>
>>
>>
>_______________________________________________
>Pw_forum mailing list
>Pw_forum at pwscf.org
>http://www.democritos.it/mailman/listinfo/pw_forum
>
>
More information about the Pw_forum
mailing list