[Pw_forum] kohn -sham orbitals ortogonality and ortonormality

Thu Aug 30 23:58:00 CEST 2012

Dear Fariba,

I think pp.x outputs give you just another representation of the orbitals in terms of the charge density. The plane wave expansion coefficients given by pw_export.x is one way to think of the orbitals, the charge density (e.g. cube files) produced by pp.x - is another. The orbitals are still orthogonal to each other (this is by construction, you have checked this with the plane wave expansion). Such orthogonality is of course not rigorous, as i pointed out in earlier messages (psi vs. Spsi), but the deviation is not very big. It is hard to say more without knowing the final goal. Hopefully this can be helpful.

Best regards,
Alexey

----- Original Message -----
From: nazari at iasbs.ac.ir
To: "PWSCF Forum" <pw_forum at pwscf.org>
Sent: Thursday, August 30, 2012 7:10:00 AM
Subject: Re: [Pw_forum] kohn -sham orbitals ortogonality and ortonormality

Dear Alexey, 

I understand that the input is for pw_export.x and run with it. 
I also need the kohn-Sham orbitals whichare produced by pp.x. but in ortogonalized form. is it possible? 
Regards 
Fariba Nazari 
IASBS 

> Dear Fariba, 
> 
> That is nice to know. Also i just found, that the example of the input i 
> sent in the previous letter is not for pp.x, but rather for 
> pw_export.x - that is for producing |psi> and S|psi>. For printing 
> orbitals you of course need pp.x. 
> Also i'm not sure what output files you mean - those with psi and Spsi 
> (pw_export.x) can be produced in either binary or text format - that is 
> it. If you imply orbitals (the charge density for given band) - i think 
> they may be written in cube format (output_format = 6, just look in 
> Doc/INPUT_PP.txt in you QE distribution for more details) 
> 
> Best regards, 
> Alexey 
> 
> 
> ----- Original Message ----- 
> 
From: nazari at iasbs.ac.ir 
> To: "PWSCF Forum" <pw_forum at pwscf.org> 
> Sent: Thursday, August 30, 2012 1:09:20 AM 
> Subject: Re: [Pw_forum] kohn -sham orbitals ortogonality and ortonormality 
> 
> 
> Dear Alexey 
> 
> Thank you . I have cheked your suggestion and it works. 
> One more question : IS it possible that the obtanied files have cube 
> format.? 
> 
> Best Regards 
> Fariba Nazari 
> IASBS 
> 
> 
> 
> 
>> Dear Fariba, 
>> 
>> I think you can get S|psi> without modifying the code. Here is an input 
>> for pp.x: 
>> 
>> &inputpp 
>> prefix = 'x', 
>> outdir = './', 
>> pseudo_dir = 'path-to-your-PP-directory', 
>> psfile(1) = 'C.pbe-van_bm.UPF', 
>> psfile(2) = 'H.pbe-van_bm.UPF', 
>> single_file = .FALSE., 
>> ascii = .TRUE., 
>> uspp_spsi = .TRUE., <--- this produces S|psi> along with the |psi>, as 
>> long as i understand this should work at least for US-PPs 
>> / 
>> 
>> In addition, if you need localized orbitals, you might look in the 
>> direction of maximally localized wannier functions, ELF, or, if you want 
>> to plot MOs, you can use the pp.x to make .xsf files with the charge 
>> density corresponding to necessary KS orbitals. 
>> 
>> 
>> Best regards, 
>> Alexey 
>> 
>> 
>> ----- Original Message ----- 
>> 
> 
From: nazari at iasbs.ac.ir 
>> To: "PWSCF Forum" <pw_forum at pwscf.org> 
>> Sent: Tuesday, August 28, 2012 10:43:52 PM 
>> Subject: Re: [Pw_forum] kohn -sham orbitals ortogonality and 
>> ortonormality 
>> 
>> 
>> 
>> Dear Alexey 
>> 
>> Would you please let me know how the S|psi> is obtained with pp.x . I 
>> need 
>> orthonormal kohn-sham orbitals. 
>> Regards 
>> Fariba Nazari 
>> IASBS 
>> 
>> 
>> 
>> 
>>> Dear Fariba, 
>>> 
>>> The Kohn-Sham (please, not kohen) orbitals produced by pp.x are not 
>>> orthonormalized in general, because of the pseudo-potentials and 
>>> projection techniques (PAW). However, practically, you may safely 
>>> assume 
>>> they are orthogonal and almost normalized (self-overlaps are not far 
>>> from 
>>> 1.0). This is especially true for norm-conserving PP (by construction, 
>>> the 
>>> wavefunctions supposed to preserve norm), and, in slightly smaller 
>>> extent, 
>>> for ultra-soft pseudopotentials. For PAW wavefunctions the trick is to 
>>> reconstruct full wavefunction from the projection, so it is S|psi>. If 
>>> i 
>>> remember it correctly, the ortogonality will then be for 
>>> <psi_i|S|psi_j> 
>>> = 
>>> delta_ij. However you can obtain S|psi> with pp.x as well as |psi>. 
>>> Please anyone correct me if i'm wrong at some point. 
>>> 
>>> Thank you, 
>>> Alexey 
>>> 
>>> ----- Original Message ----- 
>>> 
>> 
> 
From: nazari at iasbs.ac.ir 
>>> To: "PWSCF Forum" <pw_forum at pwscf.org> 
>>> Sent: Tuesday, August 28, 2012 6:23:31 AM 
>>> Subject: [Pw_forum] kohen -sham orbitals ortogonality and ortonormality 
>>> 
>>> 
>>> 
>>> 
>>> Dear All, 
>>> 
>>> Would you please let me know if the kohen -sham orbitals ,which are 
>>> obtained by pp.x, are normalized, orthogonalized or orthonormalized? 
>>> 
>>> Regards 
>>> Fariba Nazari 
>>> IASBS 
>>> -- 
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>>> -- 
>>> Dr. Alexey V. Akimov 
>>> 
>>> Postdoctoral Research Associate 
>>> Department of Chemistry 
>>> University of Rochester 
>>> 
>>> aakimov at z.rochester.edu 
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>> 
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>> -- 
>> Dr. Alexey V. Akimov 
>> 
>> Postdoctoral Research Associate 
>> Department of Chemistry 
>> University of Rochester 
>> 
>> aakimov at z.rochester.edu 
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> 
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> -- 
> Dr. Alexey V. Akimov 
> 
> Postdoctoral Research Associate 
> Department of Chemistry 
> University of Rochester 
> 
> aakimov at z.rochester.edu 
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-- 
Dr. Alexey V. Akimov

Postdoctoral Research Associate
Department of Chemistry
University of Rochester

aakimov at z.rochester.edu 