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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

Usualy convergence in ecut is considered independant from convergence in kpt. You can trust your 2 2 2 grid about that I think. It looks like there is a problem with the parallel version of abinit you use. Does it stand the parallel tests correctly ?
By the way have you tryed to see what's happening if you treat your supercell has metallic (occopt 3/4.. and tsmear)?
What do you mean when you say that Abinit crashes with occopt parameters different from zero ?
regards

Pierre-Matthieu Anglade

On 5/28/07, vincent.chevrier@dahn.phys.dal.ca < vincent.chevrier@dahn.phys.dal.ca> wrote:

Hi,
I've recently begun using Abinit and have gone through the basic tutorials. I'm trying to run an energy calculation of Li15Si4. The primitive cell is sizeable (30 Li, 8 Si) and I'm having difficulty establishing the appropriate ecut and ngkpt (or nkpt).

Here's a table of energies (in Ha). If anyone could tell me why the energy starts varying so wildly as the k points are increased or if anyone has any recommendations as to which parameters I should use I would really appreciate it!

ecut\ngkpt (nkpt)

        2 2 2 (2)       4 4 4 (6)      10 10 10 (44)   12 12 12 (68)
30      -42.500550      -42.500085      -56.940709      -43.130515
35      -42.500777      -42.500314      -61.734328       -42.554030
40      -42.500897      -42.500449      -86.955397      -149.902062
45      -42.500918      -42.500504      -42.604657      -260.973168
50      -42.500920      -42.500457      -42.566132      -158.776883
55      -42.500928      -42.500670      -44.279878      -48.285954
60      -42.500936      -42.500489      -75.221022      -43.411153

The .in, .out and log files, of the ngkpt 12 12 12 case are at the following address (if you're really interested!). The other energies were generated with the exact same input files with only the ngkpt changed.
http://myweb.dal.ca/chevrier/abinit/ecut_LDA_22.in
http://myweb.dal.ca/chevrier/abinit/ecut_LDA_22.out
http://myweb.dal.ca/chevrier/abinit/log_Li15Si4_ecut_LDA_22

I'm running this with the parallel version.
Thanks!

Vincent Chevrier
PhD Candidate
Physics Department
Dalhousie University

-- 
Pierre-Matthieu Anglade