[Pw_forum] calculation about isotope substitution

[li niu]

Dear Stefano de Gironcoli and L.F.Huang,

  Thank you so much for your help and quick reply. I understand your mean and I 
will do it right now. Thanks again for your kind help.

Wishing you a sparkling Christmas and bright happy New Year!

Best Regards,

Li Niu
Ph.D. Candidate,
Center for Composite Materials,
Harbin Institute of Technology,
Harbin, Heilongjiang, 150080, China



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[Pw_forum] calculation about isotope substitution

[lfhuang]

Dear Li Niu:
   Isotopes of one given element have the same chemical properties that is to 
say the same electronic structure,
so the electrons of the isotopes are the same from each other, and the only 
thing different is the MASS of the 
atom.So you only need to give the corresponding mass of the isotopic atom which 
you want to substitute.
In addition, are you calculating critical superconducting temperature? If you 
are, and your system is compound,
then you can calculate the isotope effect of every type of atom by this 
substitution, the formula of which is:
-d(logTc)/d(logm), 
you can refer to the paper for details:
Matteo Calandra and Francesco Mauri, "Theoretical Explanation of 
Superconductivity in C6Ca" PRL 95 237002(2005)

Yours Sincerely
L.F.Huang

> Date: Thu, 18 Dec 2008 14:58:29 +0800 (CST)
> From: li niu 
> Subject: [Pw_forum] calculation about isotope substitution
> To: pw_forum at pwscf.org
> Message-ID: 
> Content-Type: text/plain; charset="utf-8"
> 
> Dear Pwscf user,
> ?
> I'm a PWSCF user from China. I want to calculate the influence of isotope 
> substitution on the phonon modes. But I don?t know how to implement it?Any 
> help will be appreciated.
> ?
> So many thanks in advance!
> ?
> Best Regards,
> 
> Li Niu
> Ph.D. Candidate,
> Center for Composite Materials,
> Harbin Institute of Technology,
> Harbin, Heilongjiang, 150080, China

--
==
L.F.Huang(???) lfhuang at theory.issp.ac.cn
==
Add: Research Laboratory for Computational Materials Sciences,
Instutue of Solid State Physics,the Chinese Academy of Sciences,
P.O.Box 1129, Hefei 230031, P.R.China
Tel: 86-551-5591464-328(office)
Fax: 86-551-5591434
Web: http://theory.issp.ac.cn (website of our theory group)
http://www.issp.ac.cn(website of our institute)
==


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[Pw_forum] calculation about isotope substitution

[li niu]

Dear Pwscf user,
?
I'm a PWSCF user from China. I want to calculate the influence of isotope 
substitution on the phonon modes. But I don?t know how to implement it?Any help 
will be appreciated.
?
So many thanks in advance!
?
Best Regards,

Li Niu
Ph.D. Candidate,
Center for Composite Materials,
Harbin Institute of Technology,
Harbin, Heilongjiang, 150080, China


  ___ 
  ? 
http://card.mail.cn.yahoo.com/
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[Pw_forum] calculation about isotope substitution

[Stefano de Gironcoli]

change mass in the imput of the phonon code
more specifically you can generate the interatomic force constants for 
the (electronically perfect) system and then use code matdyn to generate 
a supercell and asssign different masses to different atoms (look at the 
amass and readtau variable in the input of matdyn) to study the isotopic 
effect.
stefano

li niu wrote:
>
> Dear Pwscf user,
>
>  
>
> I'm a PWSCF user from China. I want to calculate the influence of 
> isotope substitution on the phonon modes. But I don?t know how to 
> implement it?Any help will be appreciated.
>
>  
>
> So many thanks in advance!
>
>  
>
> Best Regards,
>
> Li Niu
>
> Ph.D. Candidate,
>
> Center for Composite Materials,
>
> Harbin Institute of Technology,
>
> Harbin, Heilongjiang, 150080, China
>
>
> 
> ? 
>  
>
> 
>
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