Dear Mehmet and Prof. Andrei Postnikov,
As I had mentioned earlier I had changed the vibra.h file to make maxx=10;
maxy=10 and maxz=10.
But now when I obtain the dispersion curve it is completely messed up.
I believe that something else needs to be modified in the Vibra utility in
order to accomod
Dear Mehmet,
It would be really nice of you to share that information. I'm running my
code on my personal computer and hence its taking long. (This is just a test
problem for me right now.).
Also in the Vibra utility I had to modify the vibra.h file in order to allow
me to input more supercells i.e
Mehmet,
No hurries, take your time... Unless you really wish to :)
Marcos
On Wed, Jul 28, 2010 at 9:17 PM, Mehmet Topsakal <
topsa...@unam.bilkent.edu.tr> wrote:
> OK. I will try to prepare a detailed SIESTA-PHON tutorial at this weekend.
>
>
>
> 2010/7/28 Marcos Veríssimo Alves
>
> Mehmet,
>>
OK. I will try to prepare a detailed SIESTA-PHON tutorial at this weekend.
2010/7/28 Marcos Veríssimo Alves
> Mehmet,
>
> Please do share the knowledge. It is alwayfs useful, especislly because the
> calculation of phonons is always of interest. I for one would be very much
> interested in kno
Mehmet,
Please do share the knowledge. It is alwayfs useful, especislly because the
calculation of phonons is always of interest. I for one would be very much
interested in knowing how to use Dario's code in conjunction with Siesta.
Cheers,
Marcos
On Wed, Jul 28, 2010 at 1:43 PM, Mehmet Topsaka
Thank you Prof. Postnikov and Mehmet for your quick responses. Here are a
few observations.
After Mehmets comment on increasing the Mesh cut-off I set it to 800 Ry I
still observed negative part but the magnitude has reduced. Sorry I didn't
know one had to go to such high cut-offs to observe a cha
> Hi,
> Thank you Prof. Postnikov and Mehmet for your quick replies.
>
> I do get 3 acoustic modes and 3 optical modes as I should since I just
> have
> a 2 point basis.
> The problem is that one of the acoustic mode starts from zero and goes
> negative immediately (Graph attached). I have tried in
Dear Juzar,
Your problem is related with ZA branch (so-called out-of-plane acoustical
branch) which occur around the gamma-point as an artifact of insufficient
mesh size that we encountered in some of our calculations. We usually
increase the mesh points along the z-axis so that the negative frequ
Hi,
Thank you Prof. Postnikov and Mehmet for your quick replies.
I do get 3 acoustic modes and 3 optical modes as I should since I just have
a 2 point basis.
The problem is that one of the acoustic mode starts from zero and goes
negative immediately (Graph attached). I have tried increasing the me
Dear Jusar,
The equilibrium lattice and positions that i sent to you was obtained by
LDA. You should do some lattice-relaxation if you want to use GGA. Also you
should pay attention to the significant figures. For example you should use
0.333 instead of 0.333. MeshCutoff is also important.
> Dear Mehmet,
> I used your input values but I still get a negative part in the curve. I
> tried re doing the calculation with LDA pseudo. For LDA there is no
> negative
> part whereas GGA (PBE) gives me negative part.
> Could someone comment on why this should happen for different pseudos.
Dear
Dear Mehmet,
I used your input values but I still get a negative part in the curve. I
tried re doing the calculation with LDA pseudo. For LDA there is no negative
part whereas GGA (PBE) gives me negative part.
Could someone comment on why this should happen for different pseudos. (I
dont think ther
Hello Everyone,
I'm trying to calculate the phonon dispersion relation of graphene sheet. In
this calculation I get negative frequencies. Please could someone guide me
where I'm going wrong?
These are my input files:
1) C2.fdf
SystemName graphene
SystemLabel C2
NumberOfAtoms
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