Troubleshooting Difficult Jobs

This document contains some tips for troubleshooting "failed" jobs. This document is not comprehensive, but looks to address some of the more basic failures.

Reasons for failures can best be seen by looking in the Output file, located in the Job Manager, to the right of the "Failed" message in the Job Manager. Typically, scrolling to the very end of the text-based output will give you a message as to the reason for the failure. The failure messages are often cryptic. If your job fails and you cannot determine how to fix it, send an email message via the Help Desk email request.

  1. General troubleshooting slides (Powerpoint slides in PDF format)
  2. I have a molecule that contains NH2C=O, and it always fails with MOPAC. What do I do?
    • MOPAC doesn't do well with these functional groups. The fix, however, is simple. Restart your molecule, and request the same calculation as originally desired. PRIOR to submitting your job, click on the "Advanced" tab. Under the "Keywords" box, type: MMOK. This keyword says that it is OK to try to perform this calculation with molecular mechanics mathematics. This should fix the problem.
  3. I've seen the reference to "checkpoint files" with the Gaussian software. What's up with that?
    • A Gaussian checkpoint file is a temporary storage file that contains a running check on the calculations done. If the job fails, the checkpoint file contains everything that has been calculated successfully. Once you have figured out what went wrong, you can restart your job from the checkpoint file. This reduces the amount of time needed for your job to be run. To use a checkpoint file, click on the "Save checkpoint file" under the "Advanced" tab prior to running the job. If the job fails, you can restart from the checkpoint file by going to the "Advanced" tab, and select the appropriate checkpoint file from the pulldown menu.