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[BOTTIN Francois <francois.bottin@cea.fr>]

Thanks a lot Joe and Emmanuel.
So, in conclusion, it seems that the problem is not related to the triple parallelization (paral_kgb=1) but rather comes from LOBPCG (wfoptalg=4) or nloalg=4, fftalg=401 and fft_opt_lob=2, even in sequential mode.
Thank you for this bug report Joe and Emmanuel. If you want to investigate further on your side, your help is welcomed.
On my side, I start now to solve the bug. In addition, I have to remove the nloalg limitation and clean the fft_opt_lob keyword (and also some parts of LOBPCG).
I will check if these keywords or lobpcg(cc)wf.F90 are responsible for the trouble.
If not, I will track wfoptalg=4 in the code ...
Francois

PS: I thought that the fftalg=400 (without zero padding) works in LOBPCG sequential. It seems that Joe fails but that Emmanuel succeeds ("fftalg is not concerned")?

Josef W. Zwanziger a écrit :

637400.55965.qm@web1116.biz.mail.sk1.yahoo.com" type="cite">

OK, here's some test results. One sentence summary: I *think* the problem is the wfoptalg 4 algorithm, and npband /= 1 adds a little bit too. But the biggest problem seems to be in wfoptalg 4.

Compiler: Intel 10.1 + MKL + MPICH2 compiled with Intel 10.1

System: BCC iron primitive unit cell, atompaw-generated PAW with parameters from http://www.abinit.org/PAW/MAIN/ATOMICDATA/026-Fe/ 

(this is Marc's set I believe). 

ngkpt 8 8 8

tolvrs = 1.0D-16 (extremely tight convergence to exaggerate any differences)

ecut 15

pawecutdg 30

ecutsm1 0.0

ecutsm2 0.5

1) Baseline data:

paral_kgb 0, wfoptalg = 10 (default)

Convergence at ETOT 25 and ETOT 24 in the two cases.

2) paral_kgb 0, wfoptalg 4, nloalg 4, fftalg 401:

Two cases: ETOT 24, ETOT 36

note: you can't run the defaults on nloalg and fftalg with wfoptalg 4.

3) paral_kgb 1, npband 4, npfft 1, npkpt 4, fft_opt_lob 2 together with wfoptalg 4 from above

two cases: ETOT 23, ETOT 41

4) as in 3, but npband 1, npfft 1, npkpt 4

ETOT 23, ETOT 37

5) npband 1, npfft 4, npkpt 4, otherwise as in 3

ETOT 22, ETOT 38

So, phenomenologically, the presence of ecutsm /= 0 makes convergence take 50% longer in the wfoptalg 4 case, and the further presence of npband /= 1 adds another 20%. 

 

Josef W. Zwanziger
Professor of Chemistry
Canada Research Chair in NMR Studies of Materials
Director, Atlantic Region Magnetic Resonance Centre
Department of Chemistry
Dalhousie University
6274 Coburg Road
Halifax, Nova Scotia B3H 4J3 Canada
tel: +1.902.494.1960
fax: +1.902.494.1310
web: http://jwz.chem.dal.ca
jzwanzig@jzwanzig.org,jzwanzig@dal.ca

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Francois Bottin                    tel: 01 69 26 41 73
CEA/DIF                            fax: 01 69 26 70 77
BP 12 Bruyeres-le-Chatel         email: Francois.Bottin@cea.fr
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