Re: [Wien] virtual crystal approximation

[Zhu, Jianxin]

Hello,

As I recall, it is nonessential to change the value in case.inst. But the 
change of NE in case.in2 is important.
It is straight to do so — when you change Fe 26 to 26.2 in case.struct, add 
0.2*number of Fe (in the considered unit cell)  to the existing NE.
The reason is simple --- With 26 to 26.2, the valence electron count is 
increased.

Cheers,

Jianxin

#
Jian-Xin Zhu, Ph.D
Theoretical Division, MS B262
Los Alamos National Laboratory
Los Alamos, New Mexico 87545
Phone: (505) 667 2363 (T-4);
(505) 667 6602 (CINT)
Fax: (505) 665 4063
Email (main): jx...@lanl.gov
Email (backup): physjx...@gmail.com
#

From: , Qingping mailto:qm...@bnl.gov>>
Reply-To: A Mailing list for WIEN2k users 
mailto:wien@zeus.theochem.tuwien.ac.at>>
Date: Thursday, January 15, 2015 3:21 PM
To: "wien@zeus.theochem.tuwien.ac.at<mailto:wien@zeus.theochem.tuwien.ac.at>" 
mailto:wien@zeus.theochem.tuwien.ac.at>>
Subject: [Wien] virtual crystal approximation

Dear all,
I want to do virtual crystal calculation. I change Fe’s Z to 26.2. I also 
change case.inst to:
Fe
Ar 3
3, 2, 2.0 N
3, 2, 2.0 N
3, -3, 2.5 N
3, -3, 0.0 N
4, -1, 1.0 N
4, -1, 0.7 N
I checked the Mail Archive. Someone said I also need change NE in case.in2. I 
do not know how to change it, and why I need change NE. I also do not know NE’s 
means. Could you tell me. Thank you.
Best,
Qingping Meng
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[Wien] virtual crystal approximation

[Meng, Qingping]

Dear all,
I want to do virtual crystal calculation. I change Fe's Z to 26.2. I also 
change case.inst to:
Fe
Ar 3
3, 2, 2.0 N
3, 2, 2.0 N
3, -3, 2.5 N
3, -3, 0.0 N
4, -1, 1.0 N
4, -1, 0.7 N
I checked the Mail Archive. Someone said I also need change NE in case.in2. I 
do not know how to change it, and why I need change NE. I also do not know NE's 
means. Could you tell me. Thank you.
Best,
Qingping Meng
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Re: [Wien] Virtual Crystal Approximation

[Hena Das]

Thank you for your suggestions. Yes I realize I was doing wrong. 



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] on behalf of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Thursday, December 12, 2013 1:48 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Virtual Crystal Approximation

You are not doing "virtual crystal approximation" (where one changes the
occupation by a few tenth of an electron), but you are changing the atom.

If you change Z by two, do also the initialization with an atom of 
Z=Z(W)+1,2,3,...

Am 12.12.2013 00:56, schrieb Hena Das:
> Dear All,
>
> Using Virtual Crystal Approximation I am trying to do total energy 
> calculation by varying occupancy of 5d level of W^+6 ion.
> I did a normal initialization first, and afterwards changed Z in case.struct 
> and case.in2 (not in case.inst) and then submitted a scf calculation.
> Change in occupancy by one worked well. However for higher than one, like 
> two, three or more, I got the following error:
>
> Error in LAPW1
>   'SELECT' - no energy limits found for atom   4  L= 0
>   'SELECT' - E-bottom   -3.51089   E-top -200.0
>
> I have tried all suggestions given in the "Trouble shooting", but still 
> getting the same error.
>
> Please help me to solve this problem.
>
> Thank you.
>
> Best regards,
> Hena Das
>
>
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--
-
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pbl...@theochem.tuwien.ac.at
-
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Re: [Wien] Virtual Crystal Approximation

[Peter Blaha]

You are not doing "virtual crystal approximation" (where one changes the
occupation by a few tenth of an electron), but you are changing the atom.

If you change Z by two, do also the initialization with an atom of 
Z=Z(W)+1,2,3,...

Am 12.12.2013 00:56, schrieb Hena Das:

Dear All,

Using Virtual Crystal Approximation I am trying to do total energy calculation 
by varying occupancy of 5d level of W^+6 ion.
I did a normal initialization first, and afterwards changed Z in case.struct 
and case.in2 (not in case.inst) and then submitted a scf calculation.
Change in occupancy by one worked well. However for higher than one, like two, 
three or more, I got the following error:

Error in LAPW1
  'SELECT' - no energy limits found for atom   4  L= 0
  'SELECT' - E-bottom   -3.51089   E-top -200.0

I have tried all suggestions given in the "Trouble shooting", but still getting 
the same error.

Please help me to solve this problem.

Thank you.

Best regards,
Hena Das


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--
-
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pbl...@theochem.tuwien.ac.at
-
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Re: [Wien] Virtual Crystal Approximation

[Fecher, Gerhard]

If you change Z  of (the atom you initially named) W by one, that is from 74 to 
75, then you have Re but NOT W !
Wien does not care how you name an atom but only the number of Z matters and 
Z=75 is definitely not longer tungsten.


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

Von: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at]" im Auftrag von "Hena Das 
[hd...@cornell.edu]
Gesendet: Donnerstag, 12. Dezember 2013 00:56
An: wien@zeus.theochem.tuwien.ac.at
Betreff: [Wien] Virtual Crystal Approximation

Dear All,

Using Virtual Crystal Approximation I am trying to do total energy calculation 
by varying occupancy of 5d level of W^+6 ion.
I did a normal initialization first, and afterwards changed Z in case.struct 
and case.in2 (not in case.inst) and then submitted a scf calculation.
Change in occupancy by one worked well. However for higher than one, like two, 
three or more, I got the following error:

Error in LAPW1
 'SELECT' - no energy limits found for atom   4  L= 0
 'SELECT' - E-bottom   -3.51089   E-top -200.0

I have tried all suggestions given in the "Trouble shooting", but still getting 
the same error.

Please help me to solve this problem.

Thank you.

Best regards,
Hena Das


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[Wien] Virtual Crystal Approximation

[Hena Das]

Dear All,

Using Virtual Crystal Approximation I am trying to do total energy calculation 
by varying occupancy of 5d level of W^+6 ion. 
I did a normal initialization first, and afterwards changed Z in case.struct 
and case.in2 (not in case.inst) and then submitted a scf calculation. 
Change in occupancy by one worked well. However for higher than one, like two, 
three or more, I got the following error:

Error in LAPW1
 'SELECT' - no energy limits found for atom   4  L= 0
 'SELECT' - E-bottom   -3.51089   E-top -200.0

I have tried all suggestions given in the "Trouble shooting", but still getting 
the same error. 

Please help me to solve this problem.

Thank you.

Best regards,
Hena Das


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Re: [Wien] virtual crystal approximation

[Uday]

In the present form of case.inst it is looking like a 20% hole doped.
The process is..
1. Initialize the calculation with Ba(Z=56).
2. Change Z to 55.90
3. Change case.inst to:
--
Ba
Xe 1
6,-1,1.0  N
6,-1,0.9  N
---
4. Changed NE in case.in2*
5. Run the SCF.

Regards
Uday
IIT Kanpur

>  style="font-family:굴림;font-size:10pt;">
> Hi users.I want to calculate VCA for 10% hole doping.Fist,
> edit Z of an atom in structure file.Second,   in the step of
> check case.in1_st, I face the message "error: case.inst not consistent
> with Z
> > edit case.inst and rerun
> lstart afterwards or change Z in StructGen!".  So, I modified
> the value
> thatBa   
> Xe 16,-1,1.0  N
> -> 6,-1,0.9 N6,-1,1.0 
> N -> 6,-1,0.9
> NAnd then, in case.in2 fileNE 67.8
>     ->
> 67.7I wonder that this is correct.If not,how do I edit
> the value in case.in1.Thanks for reading in
> advance.Myung-Chul.
>
>  src="https://mail3.nate.com/app/msg/confirm/?usn=62295&email=kangb...@lycos.co.kr&key=019ccf7fb4cb9b987a9fb34d66090fef$5c672...@natemail.nate.com";
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>


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[Wien] virtual crystal approximation

[kangb...@lycos.co.kr]

Hi users.I want to calculate VCA for 10% hole doping.Fist, edit Z of an atom in structure file.Second,   in the step of check case.in1_st, I face the message "error: case.inst not consistent with Z
> edit case.inst and rerun lstart afterwards or change Z in StructGen!".  So, I modified the value thatBa    Xe 16,-1,1.0  N -> 6,-1,0.9 N6,-1,1.0  N -> 6,-1,0.9 NAnd then, in case.in2 fileNE 67.8     -> 67.7I wonder that this is correct.If not,how do I edit the value in case.in1.Thanks for reading in advance.Myung-Chul.

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[Wien] Virtual Crystal Approximation (VCA): not neighboring atoms in periodic table

[Qingyun Mao]

Dear Xavier,

Thank you for your reply!

Regards,
Qingyun

Sent from my iPad

On Mar 9, 2013, at 1:14 AM, Rocquefelte  
wrote:

> Many other posts have been sent more recently. Search the word "virtual" and 
> not "VCA". 
> 
> The idea is that you replace an atom defined by a nucleus +Z surrounded by Z 
> electrons, by an effective atom defined by a nucleus Zeff = Z+x  surrounded 
> by Z+x electrons. Such an effective   treatment can only be done for 
> neigboring atoms, which have the same number of core electrons for instance 
> and similar radii...
> Indeed, remember the Slater approach (effective nucleus). The screening is 
> defined by the inner electrons Zeff = Z - Sigma, and the way the nucleus is 
> screened defines all the properties of the   atom. In your case the 
> valence electrons of La and Nb feel a completely different effective nucleus 
> (the screening is too much different) and a mixing of these two atoms cannot 
> be simply   treated by an effective nucleus. In a way VCA is a 
> perturbative approach and could give results only if the atoms are not too 
> far in the periodic table. 
> 
> In addition, as already explained by Peter in previous posts it should be 
> used only for "non-active" electrons in the valence band (like Sr2+/La3+), 
> but not for active ones (like O/F) ...
> 
> In your case, I will use a supercell approach and to insure that you didn't 
> create an artificial order you must try different models and compare them in 
> terms of total energy, DOS, properties... 
> 
> Best Regards
> 
> Xavier
> 
> 
> 
> 
> 
>  valence electrons/core charge
> 
> 
> Le 3/9/2013 1:11 AM, Qingyun Mao a ?crit :
>> Dear Prof. Blaha and wien users,
>> 
>> Recently I am trying to do calculations on systems like La(x)Nb(1-x)O(y). I 
>> searched in the mailing list and the earliest comments showed up was posted 
>> around 2004. I saw comments like: "VCA in WINE2k is only possible between 
>> neighboring elements, like Na-Mg or Ba-La." But I have not seen any 
>> explanation for that yet.
>> 
>> May I ask the reason why we cannot use VCA for atoms which are not neighbors 
>> (like La and Nb) in periodic table? Thanks a lot!
>> 
>> Regards,
>> Qingyun Mao
>> 
>> School of Applied and Engineering Physics
>> Cornell University
>> 
>> 
>> 
>> 
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[Wien] Virtual Crystal Approximation (VCA): not neighboring atoms in periodic table

[Rocquefelte]

Many other posts have been sent more recently. Search the word "virtual" 
and not "VCA".

The idea is that you replace an atom defined by a nucleus +Z surrounded 
by Z electrons, by an effective atom defined by a nucleus Zeff = Z+x  
surrounded by Z+x electrons. Such an effective treatment can only be 
done for neigboring atoms, which have the same number of core electrons 
for instance and similar radii...
Indeed, remember the Slater approach (effective nucleus). The screening 
is defined by the inner electrons Zeff = Z - Sigma, and the way the 
nucleus is screened defines all the properties of the atom. In your case 
the valence electrons of La and Nb feel a completely different effective 
nucleus (the screening is too much different) and a mixing of these two 
atoms cannot be simply treated by an effective nucleus. In a way VCA is 
a perturbative approach and could give results only if the atoms are not 
too far in the periodic table.

In addition, as already explained by Peter in previous posts it should 
be used only for "non-active" electrons in the valence band (like 
Sr2+/La3+), but not for active ones (like O/F) ...

In your case, I will use a supercell approach and to insure that you 
didn't create an artificial order you must try different models and 
compare them in terms of total energy, DOS, properties...

Best Regards

Xavier





  valence electrons/core charge


Le 3/9/2013 1:11 AM, Qingyun Mao a ?crit :
> Dear Prof. Blaha and wien users,
>
> Recently I am trying to do calculations on systems like 
> La(x)Nb(1-x)O(y). I searched in the mailing list and the earliest 
> comments showed up was posted around 2004. I saw comments like: "VCA 
> in WINE2k is only possible between neighboring elements, like Na-Mg or 
> Ba-La." But I have not seen any explanation for that yet.
>
> May I ask the reason why we cannot use VCA for atoms which are not 
> neighbors (like La and Nb) in periodic table? Thanks a lot!
>
> Regards,
> Qingyun Mao
>
> School of Applied and Engineering Physics
> Cornell University
>
>
>
>
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[Wien] Virtual Crystal Approximation (VCA): not neighboring atoms in periodic table

[Qingyun Mao]

Dear Prof. Blaha and wien users,

Recently I am trying to do calculations on systems like La(x)Nb(1-x)O(y). I
searched in the mailing list and the earliest comments showed up was posted
around 2004. I saw comments like: "VCA in WINE2k is only possible between
neighboring elements, like Na-Mg or Ba-La." But I have not seen any
explanation for that yet.

May I ask the reason why we cannot use VCA for atoms which are not
neighbors (like La and Nb) in periodic table? Thanks a lot!

Regards,
Qingyun Mao

School of Applied and Engineering Physics
Cornell University
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