I have been optimizing families of reactions and their transition states with these functional/basis sets, but for some reason the few converged geometries I've received for sn2 reactions (R-C-Cl --> R-C-F, hydrogens implied) seem to be incorrect.
Is there some settings I'm neglecting, or is 631-g not a suitable basis for sn2 reactions?
I'll attach my output file one of the files that have (somehow) converged.
Dear Skyler,
Try to use larger basis set for your calculations, 6-31G is a very smaller basis. Diffuse functions are needed for anions. Here I have attached output file generated with your system. I have used b3lyp/6-31++G** on all atoms. First try to do a restricted optimization and frequency analysis of all other cases followed by a relaxed one. Hope this helps.
Lisa
anions must have diffuse functions: ζ (zeta) controls the width of the orbital (large ζ gives
tight function, small ζ gives diffuse function). this means the electron is held far away from the nucleus. such functions are necessary for anions, Rydberg states and very electronegative atoms (fluorine) with a lot of electron density. It is very bad to do computations on anions without using diffuse functions; your results could change completely.
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