VASP
Using VASP on Improv
VASP can be loaded and unloaded with the following commands respectively (for these examples, I'm using vasp/6.4.3):
module load vasp/6.4.3
module unload vasp/6.4.3
An example script to run VASP on Bebop can be found at /soft/software/custom-built/vasp/6.4.3_st/example/vasp.pbs.
The parallel performance of VASP can be optimized with a few INCAR tags.
We recommend using NCORE and KPAR in your INCAR file on Improv to improve parallel performance.
NCORE should be set to a divisor of 16 on Improv. We find that NCORE=8 gives good parallel performance on Improv. You should test NCORE=2, 4, 8, and 16 for your case to get the optimal performance on Improv.
NCORE should be set to a divisor of 18 on Bebop. We find that NCORE=6 gives good parallel performance on Bebop. You should test NCORE=2, 3, 6, 9 and 18 for your case to get the optimal performance on Bebop.
Using NCORE=1 is discouraged except for GW and RPA calculations.
KPAR should be set to a divisor of the number of k-points.
Setting KPAR to the number of nodes being used will give the most improvement in parallel performance.
NCORE*KPAR must be a divisor of the number of cores being used.
See the VASP wiki at https://www.vasp.at/wiki/index.php/Category:Parallelization for more details.
Unfortunately, the parallel performance of VASP on will be poor when using more cores than atoms. For calculations involving multiple k-points the KPAR tag will improve parallel scaling for small cells.
You can run several VASP calculations in parallel in a single batch job to improve the efficiency of small VASP calculations. An example script to do this can be found at /soft/software/custom-built/vasp/6.4.2/example/multiple-mpi/test.sh on Improv. ```