Page 1 of 1

virtual crystal approximate

Posted: Mon May 11, 2015 5:02 am
by gswylq
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

Re: virtual crystal approximate

Posted: Mon May 11, 2015 6:48 pm
by jzwanzig
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.

Re: virtual crystal approximate

Posted: Tue May 12, 2015 2:23 pm
by gswylq
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.