Interactive Job
General
This calculation is a standard ionic and electronic energy minimisation for ethane in vacuum. Because the calculation is short, it can be run interactively from the command line. A Bash script will be used to set up and submit the calculation.
To start an interactive Slurm job, we will execute srun directly - and not from within a batch script sumitted with sbatch. Subbmitting with srun instead of sbatch makes the job execute in real time, or, in other words, reads stdin from the terminal and prints 'stdout' and 'stderr' to the terminal.
Warning
running a job in this way means if your connection with NeSI drops, the job will fail - as 'stdin' is broken. Therefore, running jobs interactively is only appropriate for short calculations or quick checks.
Input parameters
Lets start by inspecting the ./input/INCAR file.
We set the desired exchange-correlation functional with the GGA tag. Keep in mind the GGA type should match that of the POTCAR pseudopotential. If these do not match, VASP will give a warning.
DISCUSS parallelisation options used in this calc NPAR HERE
I happen to know that this calculation has 12 bands (i.e., NBANDS= 12) ...describe how we find NBANDS before running full calc here... Knowing this, lets keep it simple and submit our calculation with 12 cores, such that each band (or KS orbitals) gets its own core.
We do this by setting NPAR = 12 in the INCAR.
Start the calculation
Inspect and then execute the script start.sh (by typing ./input/start.sh). You may also wish to inspect the other files in the input directory.
Approximate runtime statistics
total cpu time (approx): XX:XX:XX
memory used:
XXX
MPI tasks:
XXX
CPU efficiency:
XXX
OpenMP threads:
XXX