[Pw_forum] Transmission calculation for simple metals
Vladislav Borisov
vladislav.borisov at physik.uni-halle.de
Wed Jul 23 09:05:51 CEST 2014
Dear all,
thank you very much for your kind help and the suggestions. As it occurs for the system
I study, larger values of ewind, indeed, solve the problem with the transmission at some
k-points, and now the convergence is achieved even for smaller epsproj < 1.e-7.
I also agree that the optimal combination of parameters (ewind, epsproj) that provides
a good convergence might be different in each case, as we noticed from the previous tests
for other systems.
Regarding the question about the structure of cobalt:
> Finally, a word about the crystal structure. Are you sure that?s what you want?
> The neighbors of the Co atoms seem to have different bond distances. Maybe you need
> to choose another value for celldm(3)?
In fact, such tetragonally distorted fcc structure is exactly what we need in our study.
I have an additional question about the delgep parameter. According to its description,
it is used for stability reasons when the eigenvalue problem is solved, and the default
value is 5.e-10. It is also clear that the minimal possible value should be used,
as long as the code doesn't crash. However, when I use the following setup for the
calculation of cobalt
ewind = 400.d0,
epsproj = 1.d-10,
delgep = 5.d-10,
nz1 = 22
the calculation ends with an error
stopping ...
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine transmit (1029):
problems with the linear system
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Getting back to values of the order of 1.e-7 solves the problem. Is it acceptable
to use such relatively large values of delgep?
With kind regards,
Vladislav Borisov
Martin Luther University Halle-Wittenberg
Von-Seckendorff-Platz 1, Room 1.17
06120, Halle (Saale), Germany
Tel No: +49 (0) 345 55-25448
Fax No: +49 (0) 345 55-25446
Email: vladislav.borisov at physik.uni-halle.de
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