1 / 3

Running VASP on the CRC: sneaky tricks (1/3)

Running VASP on the CRC: sneaky tricks (1/3). 1- NPAR: Should set it in the INCAR file to the number of cores you are running on. Time comparison (on 8 cores): ( i ) NPAR=1 Wallclock : 1d 19h (ii) NPAR=4 Wallclock : 1d 13h

edana
Download Presentation

Running VASP on the CRC: sneaky tricks (1/3)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Running VASP on the CRC: sneaky tricks (1/3) 1- NPAR: Should set it in the INCAR file to the number of cores you are running on. • Time comparison (on 8 cores): (i) NPAR=1 Wallclock: 1d 19h (ii) NPAR=4 Wallclock: 1d 13h (iii) NPAR=8 Wallclock: 1d 4hrs Con: Requires more memory 2- Choosing to run on local scratch, /pscratchor on AFS: script to run local scratch in ~/Group/bin/test_local_scratch.csh • Time comparison: (i) afs 230 seconds (ii) pscratch 474 seconds (iii) local scratch 94 seconds April 20 2011

  2. Running VASP on the CRC: sneaky tricks (2/3) 3- Doing a run for a small number of KPOINTS, copy CONTCAR to POSCAR and rerun for a high number of KPOINTS (trick done used by vasp team). • Most of the ionic steps (a factor of at least 10, much more for NEB calculations) will be done with the with the small number of KPOINTS: • e.g. (2x2x1) and then (8x8x1) for a (2x2) unit cell. • Can be done automatically in a script: April 20 2011

  3. Running VASP on the CRC: sneaky tricks (3/3) 4- If only interested in the adsorption of O, can use a small cutoff (250 eV) for adsorption energy on metal, but hard (700 eV) “pseudopotential” for dissociation of a molecule in gas phase. 5- Choose the appropriate the proper ionic relaxation algorithm (read the sessions on ionic relaxation, see VASP wiki on the CRC, especially p.25). April 20 2011

More Related