[Pw_forum] graphite cell optimization failed
germaneau at gucas.ac.cn
Wed Apr 6 19:20:36 CEST 2011
For people who are interested here is the result of my graphite
calculations including vdW-DF method from the release 4.3.
GGA GGA - london GGA -
vdW-DF LDA EXP
a = 2.46854 angs a = 2.46283 angs a = 2.47107 angs
a = 2.44424 a = 2.46067
c = 8.02141 angs (1.3514) c = 6.39949 angs (0.2705) c = 7.27887
angs (0.60887) c = 6.49579 (0.1742) c = 6.705 (6.67 at 0K)
The number in parenthesize is abs(exp-calc).
From my calculations the best option after LDA approach to include vdW
interactionsis still GGA + London.
I thank you again for your help.
On 03/24/2011 01:45 PM, Eric Germaneau wrote:
> Dear QE users,
> First of all I thank you all so much for your very useful replies and
> I did again the calculation this time using 16x16x8 k-points with cold
> smearing as suggested in PRB 71, 205214 (2005).
> I've also increased the precision of the atomic coordinates.
> Finally, I preformed the calculation using GGA only, GGA+london, and LDA.
> I got the following results:
> GGA GGA -
> LDA EXP
> a = 2.46854 angs a = 2.46283 angs a =
> 2.44424 a = 2.46067
> c = 8.02141 angs c = 6.39949 angs c =
> 6.49579 c = 6.705 (6.67 at 0K)
> energy = -155.032 energy = -155.146 ev/atom energy =
> -155.481 ev/atom
> The DFT-D approach improve significatively the length of the c axis.
> I'm currently trying to do the same thing with the vdW-DF method
> implemented in QE 4.3a but the program crash with the error:
> / from ggen : error # 45126
> too many g-vectors/
> On 03/23/2011 12:33 PM, Eric Germaneau 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,
>> /Be the change you wish to see in the world
>> / --- Mahatma Gandhi ---
>> Dr. Éric Germaneau <mailto:germaneau at gucas.ac.cn>
>> College of Physical Sciences
>> Graduate University of Chinese Academy of Sciences
>> Yuquan Road 19A
>> Beijing 100049
>> /Please consider the environment before printing this email.
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>> Pw_forum mailing list
>> Pw_forum at pwscf.org
> /Be the change you wish to see in the world
> / --- Mahatma Gandhi ---
> Dr. Éric Germaneau <mailto:germaneau at gucas.ac.cn>
> College of Physical Sciences
> Graduate University of Chinese Academy of Sciences
> Yuquan Road 19A
> Beijing 100049
> /Please consider the environment before printing this email.
> Considérez svp l'environnement avant d'imprimer cet email. /
> Pw_forum mailing list
> Pw_forum at pwscf.org
/Be the change you wish to see in the world
/ --- Mahatma Gandhi ---
Dr. Éric Germaneau <mailto:germaneau at gucas.ac.cn>
College of Physical Sciences
Graduate University of Chinese Academy of Sciences
Yuquan Road 19A
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