[Wien] lapw1 vs lapwso speed

[Peter Blaha]

This is usually not true, except when EMAX is set to 100 Ry or so.

We use for lapwso  as basisset the lapw1 eigenstates, thus the dimension 
of the lapwso eigenvalue problem is only  2 * NE, where NE is typically 
(depending on EMAX) 20-30% of NMAT of lapw1.

Am 11.06.2023 um 16:33 schrieb Yundi Quan via Wien:
> The matrix that lapw1 -up solves is the spin up part of the Hamiltonian 
> and it should be much smaller than the matrix that lapwso solves.
> 
> On Sunday, June 11, 2023, Peter Blaha <peter.blaha at tuwien.ac.at 
> <mailto:peter.blaha at tuwien.ac.at>> wrote:
> 
>     The speed of lapwso depends on EMAX in case.in1, which limits the
>     number of eigenvalues calculated in lapw1 and used as basis for lapwso.
> 
>     With EMAX=5.0 the speed of lapw1 and lapwso is usually similar.
>     With larger emax lapwso may take much more time.
> 
>     Am 11.06.2023 um 12:36 schrieb pluto via Wien:
> 
>         Dear All,
> 
>         When calculating bands for a large slab I have following sequence:
> 
>         Sun May 14 12:33:03 PM CEST 2023> (x) lapw1 -band -up -p
>         Sun May 14 02:25:26 PM CEST 2023> (x) lapw1 -band -dn -p
>         Sun May 14 04:17:22 PM CEST 2023> (x) lapwso -up -p
>         Mon May 15 01:30:05 AM CEST 2023> (x) qtl -up -p -band -so
>         Mon May 15 01:30:05 AM CEST 2023> (x) lapw2 -p -fermi -so -up
>         Mon May 15 01:51:51 AM CEST 2023> (x) qtl -dn -p -band -so
>         Mon May 15 01:51:51 AM CEST 2023> (x) lapw2 -p -fermi -so -dn
> 
>         As you can see lapwso takes much longer than lapw1 (approx. 9h
>         vs 2h). Is this normal for band calculations?
> 
>         I have 128 GB of RAM in this computer, so this is not a RAM
>         issue. Here is what top shows for the lapwso calculation (I have
>         4 parallel localhost processes in .machines, OMP=2 and no mpi):
> 
>         Tasks: 505 total,   2 running, 503 sleeping,   0 stopped,   0 zombie
>         %Cpu(s): 24.0 us,  0.2 sy,  0.0 ni, 75.7 id,  0.0 wa,  0.1 hi, 
>         0.0 si, 0.0 st
>         MiB Mem : 128047.1 total,   1845.8 free,  16809.0 used, 111158.6
>         buff/cache
>         MiB Swap:  32088.0 total,  31471.5 free,    616.5 used. 111238.1
>         avail Mem
> 
>               PID USER      PR  NI    VIRT    RES    SHR S  %CPU 
>         %MEM     TIME+ COMMAND
>         1336417 lplucin   20   0 6417856   4.8g  15840 R 199.3   3.8  
>         1294:13 lapwso
>         1336392 lplucin   20   0 2848204   2.3g  15880 S 146.8   1.9  
>         1295:30 lapwso
>         1336391 lplucin   20   0 2848188   2.4g  15916 S 130.6   1.9  
>         1304:23 lapwso
>         1336396 lplucin   20   0 2848060   2.3g  15816 S  99.7   1.9  
>         1288:06 lapwso
> 
>         .machines file:
> 
>         omp_global:8
>         omp_lapw1:2
>         omp_lapw2:2
>         omp_lapwso:2
>         1:localhost
>         1:localhost
>         1:localhost
>         1:localhost
>         granularity:1
> 
>         Best,
>         Lukasz
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> 
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>     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300
Email: peter.blaha at tuwien.ac.at    WIEN2k: http://www.wien2k.at
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