Gamma-point-only

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The gamma-point-only version of VASP is a "simplified" binary which is faster for calculations performed with integration solely over the gamma-point of the Brillouin zone. It runs "faster" for this specific settings of the KPOINTS file.

The official manual page can be found here.

Now what does it mean running "faster"? I did a short check for 4 calculations and summarized the results in the table below. The conventional binary is denoted as "complex" and the gamma-point-only binary is instinctively abbreviated as "gamma":

CPU time test on tekla2 cluster
job type queue # of cores [-] complex [hours] gamma [hours] acceleration [%]
relaxation (IBRION=1) c8m24_ompi 8 0.28 0.17 39
TS via IDM (IBRION=44) c8m24_ompi 8 6.10 4.26 30
relaxation (IBRION=1) c4m8_ompi 8 0.56 0.42 26
vibrations (IBRION=5) c8m24_ompi 8 0.84 0.69 19

The values are given for 5.2.12 and 5.2.12_GAMMA binaries as compiled by Martín at the moment. I did not happen to find any difference in the total energy, i.e. the accuracy is retained.

I encourage you to use the gamma-point-only version using

module load vasp/5.2.12_GAMMA

in your SGE script file.

Dkarhanek 12:00, 13 September 2011 (CEST)