| 1:06:09 PM PST - Sat, Mar 9th 2013 |
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I'm trying to optimize transition state structures in NWChem for ethyl bromide with iodide and propyl bromide with iodide, but am encountering some problems. Using the default convergence criteria, I was able to find a valid transition state. I want to be able to use this transition state in MOPAC to find the complexes semi-emirically, then calculate the energies for the complexes back in NWChem. The transition states I've found for ethyl bromide propyl bromide have not been successful in being used to calculate the corresponding complexes, so I've tried reoptimizing them with TIGHT convergence criteria. Propyl bromide complex calculations still have not been successful, and ethyl bromide has not been able to converge yet. I've been increasing the max iterations for ethyl, but other than this, I'm not quite sure if what else to do, or if there is anything I can change about the transition optimizations for this purpose. Any suggestions?
Also, after calculating things in vacuum, I've been optimizing the structures using COSMO to show the solvation effect of the reaction happening in acetone. It has worked with 3-21G, but when I try to run the same TS optimization with 6-311G, the transition state is found, but the vibrational frequency calculation continues to fail for MP2, though I'm not sure how to improve this for frequency calculations. Would anyone have suggestions for this also?
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