Dear Mousumi,
in addition to what María and Aleksei said a comment on your input file.
You can use SZ to see whether the phonon calculation works or not.
However, don't expect good values for the calculated frequencies with this
poor basis. You want to use DZP with a 50-100meV EnergyShift for
re
Dear Mousumi,
What you need is a supercell, which you can create with fcbuild or by
hand. Each unit cell vector must be repeated an odd number of times,
for example 3x3x3.
Then tell siesta to displace only the atoms of one unit
cell (use MD.FCfirst and MD.FClast). The condition for a good dispersi
On Tue, 10 May 2005, Mousumi Upadhyay Kahaly wrote:
| Dear All,
|
| I am trying to get phonon dispersion relation for carbon in
| diamond structure.
|
| In order to get the dynamical matrix, I use " MD.TypeOfRun FC "
| which prints out one .FC output file.
|
| The input
Dear Maria, Steffi, and all,
Thank you very much for your response. I want to
calculate the general dispersion relation for my system;
not only the phonon modes at Gamma. So, for this, how to
use "vibra package"?
Secondly, I have seen the output file. The phon
Hi Mousumi,
the atoms are moved into positive and negativ directions during the FC
run. This double the number of elements in the force constant file (pos
and neg are averaged during the vibra run).
Just a warning: with the unit cell you can only calculate the phonons at
Gamma. If you want dispe
Dear Mousumi,
your calculation is right, just that siesta calculates for positive AND
negative displacements (see output file) which are later averaged by
vibrator. So you have:
2 atoms x 3 degrees of freedom x 2 signs = 72
Regards,
Maria
_
María Machón Valbuena
Institut für F
Dear All,
I am trying to get phonon dispersion relation for carbon in
diamond structure.
In order to get the dynamical matrix, I use " MD.TypeOfRun FC "
which prints out one .FC output file.
The input structure has 2 atoms per unit cell and there are 3
degrees of freed
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