The ABINIT Users Mailing List ( CLOSED )

[Chol-Jun Yu <yucj@ghi.rwth-aachen.de>]

Dear Xiao Deng,

I am glad you got a little success. Concerning your question, Murnaghan state 
equation for non cubic unit cell, I think it is related with total energy 
according to not the lattice constant of cubic unit cell but the volume of 
the general unit cell.

So I think it would be better if you perform as follow;
1) Calculate the volumes of your hexagonal unit cells.
2) Calculate the (virtual) cubic lattice constants from the volumes.
     a=cubic root (V)
Then you can get the necessary input parameters, lattice constant : total 
energy

It is important to plan the process of the ab initio calculations by ABINIT 
carefully.

Best regards,

Yu.
On Thursday, 9. November 2006 03:17, Xiao Deng wrote:
> Dear Yu Chol Jun,
>
> Thanks for your murn program!
> Using the program, I can easily obtain equilibrium lattice constant and
> bulk modules of the cubic crystal lattice.  After carefully reading the
> source code (murn.f), However, I found the unit cell volume was calculated
> by A^3*constant, (where A is the lattice constant), which is correct only
> for the cubic lattice.  Therefore, if I would calculate the Hexagonal
> lattice, I must fix the c/a ratio and the unit cell was a^3*sqrt(3)*(c/a).
> Although it was not wrong, but it was not enough and the c/a ratio could
> also be changed.
> I think, in the input file, the a, b and c, instead of only a ,were
> supplied! Am I right? Do you have this version? I can modify the source
> code, but now I'm busy! Can you help me ?
>
> Best Wishes!
>
> Xiao Deng

-- 
Yu Chol Jun
Natural Science Center(NSC)
Kim Il Sung University, Pyongyang, DPR Korea

Computational Materials Engineering(CME)
Center for Computational Engineering Science(CCES)
Institute of Mineral Engineering(GHI)
RWTH Aachen
Mauerstrasse 5
D-52064 Aachen, Germany
Tel: ++49 241 80 94969
Fax: ++49 241 80 92271
e-mail: yucj@ghi.rwth-aachen.de
homepage: http://www.ghi.rwth-aachen.de/www/