Dear All,<div><br></div><div>I am now carrying on the calculation for a system with 2300 electrons in a 20x22x25 angstrom^3 supercell. </div><div><br></div><div>I always submit jobs on a blue-gene type machine with 512 CPUs (power 470) connected with infiniband.</div>
<div><br></div><div>In VASP, time scale for a single SCF step is about 150 sec (spin polarized, gamma point only, 400 eV energy cutoff)</div><div><br></div><div>In PWSCF, with a 25Ry energy cutoff, a single SCF step will take 3000 sec (spin polarized , gamma point only, -npool=2).</div>
<div><br></div><div>I check "massive parallel" on the manual and the arxive of this mailing list, and try to use -ntg tag when submitting the jobs but no significant improvement.</div><div><br></div><div>There is no reason that PWSCF runs 20 times slower than VASP. Does anyone have experience to improve the parallel efficiency for these large systems?</div>
<div><br></div><div>Best,<br clear="all"><br>Yuyang Zhang</div><div><br></div><div>Nanoscale Physics and Devices Laboratory<br>Institute of Physics, Chinese Academy of Sciences<br>Beijing 100190, P. R. China<br><br><br>
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