[Pw_forum] projwfc problem: sum of pdos doesn't match total dos
J. D. Burton
jlz101 at unlserve.unl.edu
Fri Aug 22 16:25:49 CEST 2008
Derek,
You should also include 3S and 3P channels, since their corresponding atomic
pseudowfcs will each contain one radial node, whereas your 2S and 2P atomic
pseudowfcs do not (or at least should not) contain any.
Cheers,
J. D.
************************************
J. D. Burton, Ph.D.
jlz101 at unlserve.unl.edu
University of Nebraska Lincoln
Physics and Astronomy
Office Ph. (402) 472 2499
213C Ferguson Hall
************************************
"The job of a scientist is to generate wrong ideas as fast as possible."
-- Murray Gell-Mann
-----Original Message-----
From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
Behalf Of stewart at cnf.cornell.edu
Sent: Wednesday, August 20, 2008 12:39 PM
To: PWSCF Forum
Subject: Re: [Pw_forum] projwfc problem: sum of pdos doesn't match total dos
Hi J. D. and Lazaro,
Thanks for your suggestions. After my last email, I actually started down
the route of adding more orbitals to the C pseudopotential by taking the
original format and switching the 3d line to
3D 3 2 0.00 0.15 1.30 1.30
before it had a -2.00 to neglect this band. I'll try it out and see how
much it affects my total density of states and see if it catches the missing
bands.
Using Wannier functions sounds interesting. I'll look into that possibility
as well.
Best regards,
Derek
J. D. Burton writes:
> Hi Derek,
>
> Interesting, though it shouldn't be that difficult to just take the
> pseudopotential (PSP) as it is and use the ld1.x program (comes with the
> espresso package) and calculate other atomic pseudowavefunctions that you
> can then project onto. You can then include these in your PSP file.
> I suppose if you're really ambitious, you could alter the projwfc program
to
> not use the atomic functions in the PSP file, but instead use different
> localized functions in a file that you provide (for example, you could try
> Wannier functions). I know that you can do this with the lda+u feature,
like
> setting U_projection_type to 'file'. See the INPUT_PW.txt file for details
> on that.
>
> Cheers,
> J. D.
>
>
> ************************************
> J. D. Burton, Ph.D.
> jlz101 at unlserve.unl.edu
> University of Nebraska Lincoln
> Physics and Astronomy
> Office Ph. (402) 472 2499
> 213C Ferguson Hall
> ************************************
> "The job of a scientist is to generate wrong ideas as fast as possible."
> -- Murray Gell-Mann
>
>
> -----Original Message-----
> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
> Behalf Of stewart at cnf.cornell.edu
> Sent: Wednesday, August 20, 2008 10:43 AM
> To: PWSCF Forum
> Subject: Re: [Pw_forum] projwfc problem: sum of pdos doesn't match total
dos
>
> Hi J. D.,
>
> Thanks for your comment! I am currently working on a project where it
would
>
> be helpful to know the orbital character of the higher energy dos peaks.
I
> know that they will have little effect on the self-consistent calculation.
>
> You raise an important point that I perhaps missed with the projwfc
> implementation. If projwfc can only map back to the orbitals provided in
> the pseudopotential (2s 2p), then this will limit its usefulness for
> determining the orbital character of higher energy conduction bands.
>
> Thanks,
>
> Derek
>
>
> J. D. Burton writes:
>
>> Derek,
>>
>> Why would you need to calculate more than 8 bands? (1 s-state + 3
> p-states)
>> x 2 C atoms per unit cell = 8 bands, and half of them are
doubly-occupied.
>> By setting nbnd = 20 (10 per atom in the unit cell) you get all the way
up
>> into d-like-bands, and your pseudopotential file doesn't contain atomic
>> d-wavefunctions of carbon. That would explain why the sum of your
> projected
>> dos doesn't match your total density, i.e. the extra peaks are d-bands.
>>
>> Cheers,
>> J. D.
>>
>> ************************************
>> J. D. Burton, Ph.D.
>> jlz101 at unlserve.unl.edu
>> University of Nebraska Lincoln
>> Physics and Astronomy
>> Office Ph. (402) 472 2499
>> 213C Ferguson Hall
>> ************************************
>> "The job of a scientist is to generate wrong ideas as fast as possible."
>> -- Murray Gell-Mann
>>
>> -----Original Message-----
>> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
>> Behalf Of stewart at cnf.cornell.edu
>> Sent: Wednesday, August 20, 2008 9:39 AM
>> To: pw_forum at pwscf.org
>> Subject: [Pw_forum] projwfc problem: sum of pdos doesn't match total dos
>>
>> Hi everyone,
>>
>> I am looking at the density of states of graphene and I have run into a
>> problem with the projwfc program. When I plot out the total density of
>> states for the system and compare this to the sum of the partial density
> of
>> states found in the pdos_tot file, I find that the sum of the partial DOS
> is
>>
>> missing some large peaks at energies above the Fermi energy. The total
> DOS
>> from the projwfc run matches the total DOS generated using dos.x and the
>> tetrahedra technique. The bands responsible for these missing peaks also
>> show up in the band plot. I have tried using both methfessel-paxton and
>> marzari-vanderbilt smearing (degauss 0.01) but this does not have any
> effect
>>
>> on the problem.
>>
>> I thought that perhaps the projection onto the atomic orbitals was
missing
> a
>>
>> significant portion of the charge, however my spilling parameter is
fairly
>
>> low 0.0116. This is comparable to the spilling parameter found in
> example08
>>
>> for nickel 0.0115 where the total and partial dos match reasonable well
>> (although slightly shifted in energy in the reference data).
>>
>> I would appreciate any thoughts as to why I am missing these DOS peaks in
>> the partial dos. Are there difficulties in projecting plane waves to
>> orbitals for conduction bands? Has anyone else run into this problem?
>>
>> For the details of my calculation, I am using C.pz-rrkjus.UPF,
ecutwfc=45,
>
>> ecutrho=450, k-grid for self-consistent calculation (64x64x1), k-grid for
>> non-scf for dos (96x96x1), number of bands=20 and working with espresso
>> 4.0.1.
>>
>> Thanks,
>>
>> Derek
>>
>>
>> ################################
>> Derek Stewart, Ph. D.
>> Scientific Computation Associate
>> http://www.people.cornell.edu/pages/das248/
>> 250 Duffield Hall
>> Cornell Nanoscale Facility (CNF)
>> Ithaca, NY 14853
>> stewart (at) cnf.cornell.edu
>> (607) 255-2856
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>
>
>
> ################################
> Derek Stewart, Ph. D.
> Scientific Computation Associate
> http://www.people.cornell.edu/pages/das248/
> 250 Duffield Hall
> Cornell Nanoscale Facility (CNF)
> Ithaca, NY 14853
> stewart (at) cnf.cornell.edu
> (607) 255-2856
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
> _______________________________________________
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################################
Derek Stewart, Ph. D.
Scientific Computation Associate
http://www.people.cornell.edu/pages/das248/
250 Duffield Hall
Cornell Nanoscale Facility (CNF)
Ithaca, NY 14853
stewart (at) cnf.cornell.edu
(607) 255-2856
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