virtual crystal approximate

External optional components of Abinit (BigDFT, Wannier90...) and codes using/providing data from/to Abinit (AtomPAW, ONCVPSP, EXC, DP, Yambo...)

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gswylq
Posts: 7
Joined: Tue Jun 17, 2014 2:07 am

virtual crystal approximate

Post by gswylq » Mon May 11, 2015 5:02 am

Dear all
i am calculating PbTi(1-x)Zrx.Using default algalch algorithm, I don't obtain the correct ground state of PbTi0.5Zr0.5 (the total energy of P4mm structure is higher than that of R3m phase). Is there other algorithms included in abinit for the mixing atoms? Ramer (Physical Review B, 62(2), R743) and Vanderbilt (Phys. Rev. B 61, 7877 (2000)) have developed two virtual crystal approximate methods in the past, but it will be difficult to use because there is not the open source code.
Thanks a lot in advance for your kind help.

Best

Qiang Li

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jzwanzig
Posts: 504
Joined: Mon Aug 17, 2009 9:25 am

Re: virtual crystal approximate

Post by jzwanzig » Mon May 11, 2015 6:48 pm

The VCA is a rather severe approximation and in my experience gives good results less often than not. You would probably be better off studying a disordered system via the special quasirandom structures approach or some other method to build an alloy model.
Josef W. Zwanziger
Professor, Department of Chemistry
Canada Research Chair in NMR Studies of Materials
Dalhousie University
Halifax, NS B3H 4J3 Canada
jzwanzig@gmail.com

gswylq
Posts: 7
Joined: Tue Jun 17, 2014 2:07 am

Re: virtual crystal approximate

Post by gswylq » Tue May 12, 2015 2:23 pm

jzwanzig wrote:The VCA is a rather severe approximation and in my experience gives good results less often than not. You would probably be better off studying a disordered system via the special quasirandom structures approach or some other method to build an alloy model.

We are very much obliged to you for your help.

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