Please help with MP2 TZ Energy calculations


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Just Got Here
Hello everyone,

I have optimized the geometries of some melatonin derivative molecules at the DFT/B3LYP/TZ level and am trying to run energy calculations at the MP2 level afterwards. The problem is that both the MP2 DZ and MP2 QZ energy calculations are finishing just fine. However, the MP2 TZ energy calculations will not converge. I have tried tightening the DFT/B3LYP/TZ geometry optimization and then running the MP2 TZ energy calculation and I have tried turning off the symmetry and automatic Z-matrix options, and neither of those tries worked either. Any suggestions at all would be much appreciated.