[Wien] (no subject)

[umbreenrasheed]

Thanks for your kind reply.I am trying to run GaN supercell with 12 parallel processors. But want to know about k points for this.Please also guide me about RTMAX 
-------- Original message --------From: Laurence Marks <L-marks at northwestern.edu> Date: 3/12/19  7:34 PM  (GMT+05:00) To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at> Subject: Re: [Wien] (no subject) 
The number of k-points needed depends upon:a) Whether you are doing a pre-convergence, e.g. MSR1a or a final convergence.b) The size of the cellc) Whether you have a metal or an insulator (partially occupied states at E_F)d) The atomic number -- high Z can converge worse -- and whether you have d/f electrons.
I would estimate that for a metal something like a k-point density of 50 nm^3 is good for reasonable precision. Divide by 2-4 for an insulator, divide by 2-4 for pre-convergence and perhaps multiply by 2-4 for phonons or high precision.
So long as memory is not an issue, you should try and divide the k-points across cores/nodes in an even fashion. It will also depend upon whether mpi or threading is better on your system, this seems to vary. It is hard to make clean statements without more information.
For a small problem (e.g. RKM=200-500) I would tend to distribute with 1-2 cores per k-point, e.g. use1:node11:node11:node11:node1
In .machines. (Add a :2 after the node1 to use mpi.) For a larger problem (e.g. RKM+12000) you probably want to just run one process. For a very large problem, e.g. RKM=30000 -- get access to a larger cluster!
Experiment.

On Tue, Mar 12, 2019 at 8:34 AM umbreenrasheed <umbreenrasheed at yahoo.com> wrote:





How many k points should be selected for 8 parallel processors selection in wein2k..
What is general relation between the two?




-- 
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.eduPartner of the CFW 100% program for gender equity, www.cfw.org/100-percentCo-Editor, Acta Cryst A
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