Dear Fei Mao,
your unit cell does not periodically repeat the graphene structure.
Further none of your calculations is converged. You should think about
your unit cell
LatticeConstant 2.44 Ang
%block LatticeVectors
13.000 0.000 0.000
0.000 13.000 0.000
0.000 0.000 4.100
%endblock LatticeVectors
and optimize the values to create an infinite graphene sheet. Then the optimization
becomes far less demanding, as no dangling bonds exist at the edge. If you desire
dangling bonds at the edge, you have to at least converge your calculations to a decent
value, which "siesta: 99 -8321.6798 -8318.5587 -8318.5639 0.9802
-4.8893" definitely is not true for dDmax=0.9802.
Good Luck
Heiko Dumlich
On 11/08/2012 09:50 AM, 毛飞 wrote:
Hi,all
Has anyone ever tried to get a well converged geometry optimization of
pure graphene, which is not passivated with any hydrogen atoms in the
edge of graphene layer. In that case, the carbon atoms in the edge of
graphene are kept with dangling bonds.
I have done this job within many codes, and all failed. I find it is
very hard to do this, but in many published scientific papers, there
are the energy band analysis of pure graphene (and sometimes adsorbed
with adatom), such as DOS, or PDOS. It is very amazing, it seems that
these authors have the pure graphene relaxed fully. Or they obtain the
band structure with not fully relaxed graphene sheet. Do you have any
ideas?
I attach the input and output files for optimizing the pure graphene
by using Siesta codes (in order to obtain the converged geometry
optimization, I have increased the MeshCutoff to 400 Ry, it still does
not work).
Any comment or suggestion is appreciated. Thank you.
Fei Mao
Beijing Normal University
--
Heiko Dumlich
Freie Universita"t Berlin
Fachbereich Physik - AG Reich
Arnimallee 14
D-14195 Berlin
GERMANY
Phone: +49-30-838 56157
