[Wien] volume_optimization

[Torsten Andersen]

Dear Mr. Thapa,

it is not unusual that the theoretical lattice constant differs by 20% 
with respect to the experimental one. You should try different 
XC-Potentials in order to see which one comes closest.

For (ii) and (iii), the lattice constants in the Wien code are the ones 
in the unit cell, so there is usually direct correspondence to experiment.

Best regards,
Torsten Andersen.


RK_Thapa wrote:
> Dear S. Cottenier,
> I have a question with regard to lattice constant by volume optimization.
> (i) For TiC case, experimental a=3.328Ang, whereas by volume optimisation it comes out quite different like a=2.734 Ang.
> (ii) Is it that we have to divide by 4 the volume obtained by volume_optimization as it TiC is a FCC structure.
> (iii) Similarly, the case of BCC crystals, we  must divide volume by 2, then we are getting the correct value of theoretical lattice constant.
> Requesting you to answer me please. Sorry for the simple question and doubt.
> Regards,
> R.K.Thapa
> Mizoram,India
> 
> 
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-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/