Always, always, always put iop(5/13=1) in your route section for D.01. It prevents a specific rounding error that causes the linker to throw a Segmentation fault when reading checkpoint files.
Here are the three most common "Off..." scenarios I’ve debugged with this specific revision, and how to fix them. The symptom: Your molecule starts optimizing fine, then suddenly the bonds stretch to 5 Angstroms, and the energy goes positive. The log file says Optimization stopped without a clear reason. Posts tagged Gaussian 09W 9.5 Revision D.01 Off...
Ghosts in the Machine: Troubleshooting Gaussian 09W Rev. D.01 (and Why You Might Still Need It) Always, always, always put iop(5/13=1) in your route
Have you found a new "Off..." bug in G09W D.01? Let me know in the comments—chances are, I’ve already lost sleep over it. The symptom: Your molecule starts optimizing fine, then
D.01 is stubborn, slow, and occasionally infuriating. But it is consistent .
Gaussian 09W 9.5 Revision D.01