Talk:Mod:joc12

Fair attempt to complete the full breath of the exercise. Confusion with gauche and anti conformations when discussing most stable form of 1,5-hexadiene. Not clear on what the analysis of thermochemistry at 0K consisted of. The main purpose to run a frequency calculation in this exercise is to find the nature of stationary points that result from a converged optimization: if all frequencies are real, the geometry is a minimum; if one frequency is imaginary it is a transition state; if more then one imaginary frequency it is a higher order saddle point (in the context of the exercise, these are rare, so you should check if the geometry is indeed optimized. i.e. Is the gradient = 0?). A frequency calculation is mandatory for every optimized structure. The orbital diagram of the cyclohexa-1,3-diene and maleic anhydride reaction transition state is interesting, but does the transition state HOMO really result from the designated reactant orbitals? Reported many failed calculations and an effort to try solutions. However an error with reference C:\G09W\l9999.exe is uninformative. A better solution to address issues is to look inside the log file for potential errors and warnings. Some misconceptions about Hartree-Fock, DFT and basis sets. Hartree-Fock does not take electronic correlation into account (although it does account for exchange correlation!) while DFT does. Jbettenc (talk) 11:29, 4 December 2014 (UTC)