[Wien] A question about the Rkm

[Laurence Marks]

A RKMAX (the RKM value in case.scf) of 2.05 is too small for a minimum RMT
of 1.2, the results of the calculation will be very poor. I estimate that
you need a value of at least 5, which will mean a much larger matrix size
and a longer calculation.

You need to use a more powerful computer or (better) a cluster. I will
estimate that something like 64 cores will give you a fairly fast result.
If all you have is a single core computer either give up on the calculation
or increase NATMAX & NUME and (if you have enough memory) wait.

N.B., depending upon your architecture the multithreaded mkl (which you
seem to be using) is faster or slower than mpi. On my systems mpi is faster
even for small system, on Peter Blaha's he says that the multithreading is
faster.

On Fri, Jan 8, 2016 at 12:28 AM, Hu, Wenhao <wenhao-hu at uiowa.edu> wrote:

> Hi, all:
>
> I have some confusions on the Rkm in calculations with 50+ atoms. In my
> wien2k, the NATMAX and NUME are set to 15000 and 1700. With the highest NE
> and NAT, the Rkmax can only be as large as 2.05, which is much lower than
> the suggested value in FAQ page of WIEN2K (the smallest atom in my case is
> a H atom with radius of 1.2). By checking the :RKM flag in case.scf, I have
> the following information:
>
> :RKM  : MATRIX SIZE 11292LOs: 979  RKM= 2.05  WEIGHT= 1.00  PGR:
>
> With such a matrix size, the single cycle can take as long as two and half
> hours. Although I can increase the NATMAX and NUME to raise Rkmax, the
> calculation will be way slower, which will make the optimization
> calculation almost impossible. Before making convergence test on Rkmax, can
> anyone tell me whether such a Rkmax is a reasonable value?
>
> If any further information is needed, please let me know. Thanks in
> advance.
>
> Best,
> Wenhao
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-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu
Corrosion in 4D: MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
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