Whats wrong with my Gaussian resource requests?
When submitting Gaussian jobs to PBS, you have to specify resource requirements in two places. What you specify as qsub options (-lvmem etc) are what is reserved for your jobs use. Gaussian knows nothing about these reservations, eg. specifying qsub -lncpus=4 will not cause Gaussian to use 4 cpus. You tell Gaussian what resources to actually use in your Gaussian input file with directives like %mem and %nproc. Naturally, whatever you tell Gaussian to use should fit inside what you have requested PBS to reserve for your job. Obviously what you specify with -lncpus should be reflected in the Gaussian %nproc line. For memory requests, the %mem line in your Gaussian input file specifies the work area that Gaussian uses. Gaussian also needs memory for the program, other data and shells etc. To safely allow for this other memory, the %mem value should be about 500-600MB less than the PBS -lvmem value (possibly more in some cases). You can tune this difference with experience by comparing the
