[Wien] insufficient virtual memory

[Hajar Nejati]

dearOleg
I mention the points that I think can be benefit to solve my problem:


1. The origin cell has these lattice constant: a=b=2.53 and c=15.0 Angstrom.
2. 4×4×2 refer to the dimensions of supercell while the k-mesh is 24 k-points in irreducible Brillouin zone (9×9×2).
3. I run lapw1 -nmat_only then I saw 14136 in case.nmat_only file (that is greater than 10000). So I had to increase NMATMAX to 20000 and compile wien2k again and rerun the scf calculation with lower RKMAX (=2).

Is there any suggestion except considering a parallel MPI version? (I use .machines file to do parallel calculation)
Thanks a lot, again.
Best Regards
Hajar




________________________________
 From: Oleg Rubel <orubel at lakeheadu.ca>
To: wien at zeus.theochem.tuwien.ac.at 
Sent: Monday, June 10, 2013 1:17 PM
Subject: Re: [Wien] insufficient virtual memory
 

Dear Hajar,

> I was trying to do a supercell calculation (hydrogenated graphenewith 64
> atoms) within 4×4×2.

It is unlikely to run such a job on a single processor. You need to consider a parallel MPI version (see Sec. 5.5 of the UG).

Does 4×4×2 refer to the k-mesh? If yes, this is too dense. Most likely you can go with a single k-point.

> When I run scf, this message appears:
> Lapw0 end
> severe (41): insufficient virtual memory
> lapw1c unknown
> lapw1c unknown
> lapw1c unknown
> (To be sure, I have searched all the previous emails on this topic, but
> failed to solve my problem.)
> I know that RKMAX should be small and NMATMAX large (I increase NMATMAX
> from 10000 to 20000 and NUME to 1500). The scf runs without error
> massage when I decrease RKMAX to 2, but the total energy NOT converge
> (when I set RMT of H atoms to 0.6, the error remains).

The purpose of NMATMAX is to prevent the calculation from crashing when the matrix size increases. Wien2k does it by lowering the effective RKmax, which you can find in the *scf file. However, changing NMATMAX is not a solution for this problem.

I would also suggest to reduce the disparity between RMTs as much as you can.

I hope this will help.


Best regards
Oleg
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