[Wien] parallel wien2k

[Laurence Marks]

Several points:

1) You only use "-fc X" for a structure with variable atomic
positions, and the TiC example has none so it will report that there
are no forces (but this should not stop the calculation).

2) The "NaN" in your case.vns file means that something went wrong in
the lapw0 call, which is why lapw1 is crashing. It is safer to delete
the case.vns file.

3) Are you using single core CPU's or multicore? The normal format for
a parallel lapw0 call (using mpi) is

lapw0: nx1:2 nx62:2 -- please note the space after the ":", it often matters

To do this you have to have mpi installed and have compiled lapw0_mpi.
If you do not have it you can use

lapw0: nx1

This will run a serial lapw0 on nx1

4) All the above assumes that you have local control of what nodes you
can use rather than this being controlled by a queuing system such as
pbs. If you are using pbs or similar then you have to have a script to
generate the .machines file since you do not know what machines to use
(unless you are running interactively).

5) The script you have will run serial (i.e. not mpi) lapw1, 2
k-vectors on nx1 and 2 on nx62. If you want to have these run using
the parallel versions (i.e. lapw1_mpi) you would need to use

1:nx1:2
1:nx62:2

(Note no space after the ":").

Whether it is faster to run with 2 processors on nx1, as against 2
different k-points will depend upon your cpu's. For a simple
calculation such as TiC it will be hard to see much difference, but
this can matter for larger ones. Be aware that if (for instance) you
had 4 processors on nx1 it may be a bad idea to use

1:nx1:2
1:nx1:2

because some variants of mpi will launch both lapw1_mpi jobs on the
same cores (CPU_AFFINITY is often the relevant flag, but this varies
with mpi flavor).

2010/2/22 zyzhang <zyzhang at stanford.edu>:
> Dear All,
>
>
>
> I am trying to test wien2k in parallel mode and I got into some problem. I
> am using
>
>
>
> run_lapw -p -i 40 -fc 0.001 –I
>
>
>
> If I use a number of 0.001 for the option fc above, I got the following
> error:
>
>
>
> Force-convergence not possible. Forces not present.
>
>
>
> If I do not use a number for the –fc option, but use “run_lapw -p -i 40 -fc
> –I” instead
>
>
>
> Then lapw0 finishes without a problem but the program doesn’t branch to
> lapw1. An error message is generated when doing the test
>
>
>
> “if ($fcut == "0") goto lapw1
>
>
>
> I was able to do “run_lapw -p -i 40 –I”, without the “-fc” option at all and
> was able to finish “lapw0 –p” and then start “lapw1 –p” but got into the
> following error:
>
>
>
> error: command   /home/zzhang/wien2k/lapw1para lapw1.def   failed
>
>
>
> Does anybody have similar problems and know how to fix this?
>
>
>
> It does the following:
>
>
>
> running LAPW1 in parallel mode (using .machines)
>
>
>
> and the .machines file is as follows:
>
>
>
> #
>
> lapw0:nx1  nx1  nx62  nx62
>
> lapw1:nx1  nx1  nx62  nx62
>
> lapw2:nx1  nx1  nx62  nx62
>
> 1:nx1
>
> 1:nx1
>
> 1:nx62
>
> 1:nx62
>
> granularity:1
>
> extrafine:1
>
>
>
> Thanks,
>
> Zhiyong
>
>
>
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>
>



-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.