1. Make a new directory and copy the Gaussian frequency output file (freq.log) to the directory.
  2. Generate Densum input file based on the freq.log:  ~/gaussian/freqlog2den.py file-name-freq-log Egrain1 Imax1 Isize Emax2
    • Egrain1: energy grain in units of cm-1. Typical choices: 5 cm-1.
    • Imax1: number of array elements in first segment of double array. If the highest vibrational wavenumber is close to 4000 cm-1 and Egrain1=5, you can set Imax1=1000 (at least greater than 801).
    • Isize: total size of double array (number of elements). Can be double of Imax1.
    • Emax2: maximum energy (cm-1) for calculation. Should be high enough so that non of the stochastic trials attempt to reach a higher energy. Suggest: 65000 cm-1.
  3. [Optional] It’s not ideal to perform computation on the login node. If the molecule is very large, suggest to get an interactive node first. For example: srun -p ilahie -A ilahie --nodes=1 --ntasks-per=node=4 --time=00:10:00 --mem=100G --pty /bin/bash.
  4. In the directory run /sw/contrib/multiwell-2022/bin/densum. You should see the output within 1 minute!

References