[Wien] Memory in the k-parallel method exceeds NMATMAX ?

[Peter Blaha]

You did not specify the corresponding :RKM values, which lists the 
actual matrix size in your calculations.

Two remarks:   the quoted numbers are typical averages with "sensible 
RMTs and close-packed structures.

I do not understand / believe the supercell sizes. What is a supercell 
with 17 atoms ? How do you create from 10 atoms --> 17 atoms ??

What are your RMT values ???


PS: k-parallel means you are using    n   lapw1  runs, and each of them 
requires the same memory. So of course, when running on a single cpu n 
k-parallel jobs, you need n times the memory of a single calculation.

Am 05.07.2018 um 16:32 schrieb Luc Fruchter:
> [ ... I apolodgize for having not responded yet to a pending discussion 
> that I already have for another subject - and probably to this one also 
> for a while, but the mail archive webmaster agrees than one cannot 
> answer with 'reply button' until this is fixed ...]
> 
> Here is my problem,
> 
> I am running cases of supercells of different sizes, using the 
> k-parallel method. To make it simple, I only consider a 10 cores machine 
> running these cores locally.
> 
> The machine has 32 Gb memory, and NTMATMAX was set according to the 
> installation suggestion:
> 
> NTMATMAX = 19000 (2 Gb)
> NUME = 6000
> 
> The cases I have run presently are from group 26 (no inversion), with 
> number of atoms ranging from 10 to 22, depending on the supercell size.
> 
> I find the following memory requirements, using k-parallel method, fixed 
> k grid and default RKMAX:
> 
> Number of atoms / memory per CPU used
> 10 / 1.7 Gb
> 12 / 2
> 15 / 2.7
> 17 / 3.1
> 22 / 4.3
> 
> So, this exceeds what I expected to be the maximum limit (from manual p. 
> 255 ~ 2 Go / CPU) and precludes the computation of larger cells, using 
> reasonable memory (3-6 Gb / CPU). Increasing the number of CPU will not 
> solve the problem, as the memory per CPU needed appears proportional to 
> the number of these CPUs.
> 
> Could someone recall the general principles for memory usage estimate in 
> the k-parallel method, and how I could be able to run larger cells 
> within these principles ?
> 
> 
> Thanks
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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