[Pw_forum] Re : graphite cell optimization failed

[Masoud Nahali]

Dear Eric

Try london="true" to get improved answer; as you should know DFT is weak
to calculate dispersion forces and by using the keyword one can include
these forces semi-empirically. I hope it helps.

Best Wishes

 Masoud
--------------
Masoud Nahali, Sharif University of Technology


Eric Wrote:

Dear all,

I'm trying to optimize unit cell parameter of graphite.
The problem is the c axis gets too long.
Starting from published data my initial parameters are a=4.59203 Bohr
and c=12.513 Bohr.
The final values are 4.664 and 15.829 respectively.
I need someone to explain to me what I did wrong, I've attached my input
file.
That's a basic calculation so it's very frustrating to not make it done.
I thank you in advance,

                                     Eric.

-- 
/Be the change you wish to see in the world
/ --- Mahatma Gandhi ---

Dr. Éric Germaneau <mailto:germaneau at gucas.ac.cn
<http://www.democritos.it/mailman/listinfo/pw_forum>>

College of Physical Sciences
Graduate University of Chinese Academy of Sciences
Yuquan Road 19A
Beijing 100049
China
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