Re: [Wien] we need to Alm(k) and Blm(k) coefficients

[Gavin Abo]

No, it seems that it is because the x_lapw script no longer writes the 
file definition line to lapw2.def unless you use the -almd [ 
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08588.html 
] or -alm switch.


So you either have to use those switches shown on page 58 of the WIEN2k 
14.2 usersguide [ http://www.wien2k.at/reg_user/textbooks/usersguide.pdf 
], modify lapw2.def by hand and use lapw2 lapw2.def, or modify x_lapw 
(e.g., remove "if ($?alm)" from the beginning of line 817).


Note, it looks like case.almblm likely has two different formats: One 
for "x lapw2 -alm" and the other for "x lapw2 -almd".


It looks like "x lapw2 -almd" is used for wien2triqs, see:

https://triqs.ipht.cnrs.fr/1.1/applications/dft_tools/Ce-HI.html

It looks like "x lapw2 -alm" is used for wannier-proj, you can see 
"wannier-proj_manual.pdf " at:


https://github.com/jeandiehl/wannier-proj/tree/master/doc

On 10/20/2016 6:56 AM, Uichiro Mizutani wrote:

Dear Professor Blaha,

We have another inquiry about the coefficients of APW+lo wave 
function, Alm(k) and Blm(k). According to the users guide, we can 
generate case.radwf and case.almblm files by replacing TOT at the top 
of case.in2 by ALM. By this operation, we could get only the 
case.radwf file but not case.almblm. It is stated that the file.almblm 
is very big. Is this the reason why the case.almblm cannot be generated.


Could you advise us how to generate the case.almblm file?

Best regards,

Uichiro

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Re: [Wien] Fermi level

[Laurence Marks]

A small comment: the definition of fermi energy, fermi level and chemical
potential is a question of semantics and confusion, see for instance
http://physics.stackexchange.com/questions/30922/whats-the-difference-between-fermi-energy-and-fermi-level

Since this is primarily a physics forum, it is probably best to stay with
the Fermi energy as T=0K and Fermi level = chemical potential at T > 0K.

If you use TEMPS in case.in2(c) an approximation of the chemical potential
is printed out. For a metal or small-gap insulator (semiconductor) it is
quite good; for a large-gap insulator for numerical reasons it is not right.

On Thu, Oct 20, 2016 at 8:39 AM, Fecher, Gerhard 
wrote:

> The definition of the FERMI ENERGY that I gave is correct for every
> material: The Fermi energy is the energy of the highest occupied state at
> Zero temperature.
> It does not depend wheter or not your material is a metal, an intrinsic
> semiconductor, an doped semiconductor, an insulator, or anything else.
>
> Indeed, for metals the Fermi energy corresponds to the chemical potential
> (the quantity  that enters the Fermi-Dirac distribution)  at Zero
> temperature.
> but the chemical potential of a metal will also depend on temperature
> (Note: the chemical potential, not the Fermi energy, depends on
> temperature.).
>
> The Zero used in the electronic structure plots (DOS, band structure,
> etc.) of Wien2k is the Fermi energy as defined above,
> therefore, it is correct to have the Zero at the top of the valence band.
>
> By the way, you never defined what you mean with "Fermi level" and why it
> must be in the middle of the band gap.
> If you define for whatever reason that "Fermi level" is "the energy in the
> middle of the band gap" then your question does not make sense.
> However, if you like to stay with youre middle of the gap definition, then
> you should give a mathematical and physical proof that this is something
> usefull for all shapes of the density of states of a semi-conductor.
>
> If you like to know where the chemical potential in a certain
> semi-conducting material is then you may check with Boltztrap,
> you have to do the same that I did when its still not implemented there ,
> change the code to include it.
>
> Just to mention, it is not my habit to answer questions about Wien2k that
> are send directly to me, please use the forum.
>
> Ciao
> Gerhard
>
> DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
> "I think the problem, to be quite honest with you,
> is that you have never actually known what the question is."
>
> 
> Dr. Gerhard H. Fecher
> Institut of Inorganic and Analytical Chemistry
> Johannes Gutenberg - University
> 55099 Mainz
> and
> Max Planck Institute for Chemical Physics of Solids
> 01187 Dresden
> 
> Von: tarek.ben-n...@laposte.net [tarek.ben-n...@laposte.net]
> Gesendet: Donnerstag, 20. Oktober 2016 14:48
> An: Fecher, Gerhard
> Betreff: Re:Fermi level
>
> Dear Gerhard,
>
> Thank you for your reply but this definition of Fermi level is correct for
> a metal and not for a semiconductor so in band structure putting fermi
> level at the top of valence band is wrong.
>
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>



-- 
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A
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Re: [Wien] Fermi level

[Fecher, Gerhard]

The definition of the FERMI ENERGY that I gave is correct for every material: 
The Fermi energy is the energy of the highest occupied state at Zero 
temperature.
It does not depend wheter or not your material is a metal, an intrinsic 
semiconductor, an doped semiconductor, an insulator, or anything else.

Indeed, for metals the Fermi energy corresponds to the chemical potential (the 
quantity  that enters the Fermi-Dirac distribution)  at Zero temperature.
but the chemical potential of a metal will also depend on temperature (Note: 
the chemical potential, not the Fermi energy, depends on temperature.).

The Zero used in the electronic structure plots (DOS, band structure, etc.) of 
Wien2k is the Fermi energy as defined above,
therefore, it is correct to have the Zero at the top of the valence band.

By the way, you never defined what you mean with "Fermi level" and why it must 
be in the middle of the band gap.
If you define for whatever reason that "Fermi level" is "the energy in the 
middle of the band gap" then your question does not make sense. 
However, if you like to stay with youre middle of the gap definition, then you 
should give a mathematical and physical proof that this is something 
usefull for all shapes of the density of states of a semi-conductor.

If you like to know where the chemical potential in a certain semi-conducting 
material is then you may check with Boltztrap,
you have to do the same that I did when its still not implemented there , 
change the code to include it.

Just to mention, it is not my habit to answer questions about Wien2k that are 
send directly to me, please use the forum.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."


Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden

Von: tarek.ben-n...@laposte.net [tarek.ben-n...@laposte.net]
Gesendet: Donnerstag, 20. Oktober 2016 14:48
An: Fecher, Gerhard
Betreff: Re:Fermi level

Dear Gerhard,

Thank you for your reply but this definition of Fermi level is correct for a 
metal and not for a semiconductor so in band structure putting fermi level at 
the top of valence band is wrong.

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[Wien] we need to Alm(k) and Blm(k) coefficients

[Uichiro Mizutani]

Dear Professor Blaha,

We have another inquiry about the coefficients of APW+lo wave function, Alm(k) 
and Blm(k). According to the users guide, we can generate case.radwf and 
case.almblm files by replacing TOT at the top of case.in2 by ALM. By this 
operation, we could get only the case.radwf file but not case.almblm. It is 
stated that the file.almblm is very big. Is this the reason why the case.almblm 
cannot be generated.

Could you advise us how to generate the case.almblm file?

Best regards,

Uichiro 

2016/10/15 0:14、Peter Blaha  のメール：

> I can confirm that 2 l-values per atom do not work with lapwso, but should 
> work with lapw1.
> 
> However, I do not have a fix for this and in fact I do not really plan to 
> introduce one, since I do not believe in putting U on two different l values 
> for the same atom is good physics.
> 
> For instance in your Gd example, the Gd-d states are too delocalized to be 
> treated with LDA+U. If you feel that GGA does not describe them well, use 
> mBJ+U.
> 
> I will, however, introduce a stop in lapwso so that the program does not run 
> (and neglects the first U value without telling you).
> 
> Peter Blaha
> 
> On 10/13/2016 10:47 PM, Laurence Marks wrote:
>> I am 99.9% certain that 2 U's for a given atom (orbital potentials) is
>> not supported in the version of lapwso that is available on the web.
>> Peter and/or Fabien may be able to provide you with a patched version
>> which will support 2 U's for a given atom.
>> 
>> On Thu, Oct 13, 2016 at 2:10 PM, Hung Yu Yang > > wrote:
>> 
>>Dear wien2k users,
>> 
>>I am using wien2k 14.2 version to try to reproduce the GdSb
>>calculation in the following paper (see FIG.5 and FIG.6):
>> 
>>
>> http://journals.aps.org.proxy.bc.edu/prb/abstract/10.1103/PhysRevB.74.085108
>>
>> 
>> 
>>I first did the calculation without SOC (LDA+spin-polarized+U), with
>>the following .indm file:
>> 
>>-- top of file: case.indm 
>>-12. Emin cutoff energy
>>1 number of atoms for which density matrix is calculated
>>1 2  2 3 index of 1st atom, number of L’s, L1
>>0 0 r-index, (l,s)-index
>>--- bottom of file 
>> 
>>Similar changes were done in .inorb file. The result is satisfactory
>>in this case, as can be seen in the following link:
>> 
>>
>> https://www.dropbox.com/s/fnqxvpgu3a8e3zg/GdSb_BS_woSOC_sp_d_f_dandf.pdf?dl=0
>>
>> 
>> 
>>In the two panels at the bottom, the gap around EF was open (from U
>>on d) and the f band was pushed down, which means the effects of U
>>on both d and f orbitals are well-considered.
>> 
>>Then I tried to do the calculation with SOC
>>(LDA+spin-polarized+U+SOC), and the result can be seen in the
>>following link:
>> 
>>https://www.dropbox.com/s/6cfbwu7yxcqxgsm/GdSb_SOC_bs.pdf?dl=0
>>
>> 
>> 
>>At the bottom right panel, although I tried to use the similar
>>setting to put U on both d and f, the effect of U only showed up on
>>d orbital (f orbital is not pushed down.) When I checked the
>>.outputorbup file, it shows
>> 
>> 
>> 
>>Calculation of orbital potential for spin block: up
>> Type of potential:LDA+U
>> Vorb applied to atom   1 orbit. numbers   2   3
>>  Fully Localized Limit method
>>Atom  1 L=  2 U=  0.250 J=  0.000 Ry
>>Atom  1 L=  3 U=  0.600 J=  0.000 Ry
>>  end of OP input
>> STRUCT file read
>>  VSP read
>> Atom  1 L= 2 spin of potential; Lx, Ly, Lz=  0.00  0.00
>>-0.025894
>> Atom  1 L= 3 spin of potential; Lx, Ly, Lz=  0.00  0.00
>> 0.003863
>> atom  1 L= 2 projection of L on M=   -0.012830
>> atom  1 L= 3 projection of L on M=0.158098
>>  natom   1
>>  No old potential found
>> Slater integrals F0, F2, F4   0.250   0.000   0.000 Ry
>> Ecorr0.00011 Mult  1 Eldau0.01465 Edc   

Re: [Wien] What's the difference between the spin-polarized and the non spin-polarized calculations

[Abderrahmane Reggad]

Thank you Dr Gavin and Dr Gerhard for your answers. The were really very
fruitful for me.

We can consider that the non spin-polarized is a special case of the
spin-polarized case. therefore we can use the equations  of the general
case to get the equations of the special case.

So we can make B_eff = 0 to get the non-polarized case, and the results
will be different as the energies.

another question: How can explain that at the level of the paired and
unpaired electrons?

Will we force the unpaired electrons to be paired one or something other ?

Thank you for your interesting

-- 
Mr: A.Reggad
Laboratoire de Génie Physique
Université Ibn Khaldoun - Tiaret
Algerie
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Re: [Wien] Fermi level

[Fecher, Gerhard]

The Fermi energy is the energy of highest occupied state at zero temperature by 
definition,
therefore, it is in semiconductors always the top of the valence band.

Everything else will be an arbitrary choice !  (Or are there any occupied 
states inside of the gap ? ;-)

Do not confuse the Fermi energy with the chemical potential that enters the 
Fermi-Dirac distribution.

I guess the thing you call "Fermi-level" is never clearly in the middle of the 
band gap (or only by chance), 
because its position depends not only on the temperature and the doping of the 
semi conductor but also
on the shape of the density of states in the valence and conduction bands.

Too bad that sometimes even textbooks use "laboratory slang" rather then clear 
well defined expressions.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."


Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden

Von: Wien [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von 
tarek.ben-n...@laposte.net [tarek.ben-n...@laposte.net]
Gesendet: Donnerstag, 20. Oktober 2016 10:33
An: wien@zeus.theochem.tuwien.ac.at
Betreff: [Wien] Fermi level

Dear Wien users,
I have searched in the archives to understand why the fermi level is at the 
maximum of the valence band in band structure plot of a semiconductor, I found 
that it was an arbitrary choice but untill now i can't explain this from a 
physical point of view since for me the fermi level must be in the middle of 
the gap.

Thank you for your help
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[Wien] Fermi level

[tarek . ben-nasr]

Dear Wien users, 
I have searched in the archives to understand why the fermi level is at the 
maximum of the valence band in band structure plot of a semiconductor, I found 
that it was an arbitrary choice but untill now i can't explain this from a 
physical point of view since for me the fermi level must be in the middle of 
the gap. 

Thank you for your help 
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Re: [Wien] What's the difference between the spin-polarized and the non spin-polarized calculations

[Fecher, Gerhard]

I guess the answer is basic calculus
B_eff = V_up - V_dn
is zero when V_up = V_dn and the equations in the spin polarized and the non 
spinpolarized case become the same, isn't it.
(Note: V_up=V_up(rho_up) and V_dn=V_dn(rho_dn) is used for short, the densities 
rho_up and rho_dn are calculated 
from the Kohn-Sham wave functions the V(rho) depend on the used 
exchange-correlation functional.)

Just take a pencil and write down the equations given in the trancparencies or 
textbooks and proof that I am right by
setting B_eff=0.

... or you finally did not understand what a selfconsistent field calculation 
means, 
then you have to attend some basic courses on mathematics or theoretical 
physics.


Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."


Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden

Von: Wien [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von Gavin Abo 
[gs...@crimson.ua.edu]
Gesendet: Donnerstag, 20. Oktober 2016 07:30
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] What's the difference between the spin-polarized and the 
non spin-polarized calculations

You likely have to derive the Kohm–Sham equations and solve them for the 
wavefunction solutions (and look into the WIEN2k source code) for the detailed 
answers to your questions.  I haven't done it myself, so I cannot help you 
there.  I think the go to references for that were:

Planewaves, Pseudopotentials and the LAPW Method by David J. Singh and Lars 
Nordström [ http://link.springer.com/book/10.1007%2F978-0-387-29684-5 ]
http://www.wien2k.at/reg_user/textbooks/double_counting.pdf
http://www.wien2k.at/reg_user/textbooks/DFT_and_LAPW_2nd.pdf

My attempt at general answers:

No parameters are monitored to make the 2 densities equal.  As seen on slide 21 
of http://www.wien2k.at/events/ws2015/rolask_rela.pdf , there are two 
equations, one for Psi_up and one for Psi_down, but for the non-spin polarized 
case both equations are the same such that Psi_up = Psi_down = Psi.  So only 
one equation for the wavefunction Psi needs to be solved for.  As seen on slide 
66 in http://www.wien2k.at/events/ws2015/WS22-KS-DFT-LAPW.pdf , the calculation 
is given an initial charge density (during init_lapw), then the charge (and 
spin) density should be computed from the self consistent field (scf) cycles 
(run_lapw).

On the other hand, the spin-polarized calculation (runsp_lapw) has to solve two 
separate equations instead of one as shown on slide 24 in rolask_rela.pdf. 
Which is why for example there is lapw1 -up and lapw1 -dn for the 
spin-polarized calculation and only just lapw1 for the non-spin polarized.  The 
simplified equations it uses for the spin-polarized case was made possible by 
choosing the z-axis for the direction of the magnetic field [ Ab Initio Study 
of NiO-Fe Interfaces: Electron States and Magnetic Configurations by L. D. 
Giustino, 
http://www.nano-phdschool.unimore.it/site/home/phd-students/documento102017667.html
 (page 24) ].

The Bef term is crossed out on slide 21, so there should be no exchange 
magnetic potential Bxc, since Bef = Bext + Bxc (from slide 19).  However, 
whether Bef term is not there or how the Bef term is set to 0, I don't know and 
someone else might; I didn't look into the source code to try to determine that.

On 10/19/2016 5:18 PM, Abderrahmane Reggad wrote:

Thank you Dr Gavin for your reply and also for your interesting for my 
questions.

I have checked the 2 presentations but I didn't find what I look for .

It's mentionned that in non spin-polarized calculation the spin-up density = 
the spin-down density . Which parameters are they monitored to make these 2 
densities equal. I have read that in this case the exchange magnetic potential 
will be equal to zero. I want to know if it's so or not .

Best regards
--
Mr: A.Reggad
Laboratoire de Génie Physique
Université Ibn Khaldoun - Tiaret
Algerie
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