Talk:Mod:physical module3

Grade A:

Cope: Nice and clearly laid out – good introduction and initial analysis of conformers, though maybe some pictures would have helped your reasoning of why the gauche 3 is lowest in energy Nice to see log files uploaded 0K energies – at 0K we’d expect NO thermal energy (as the molecules are not moving). We’d only expect the zero point energy to be added on, as ZPE does not depend on temperature. Looking at your input files, unfortunately Gaussian takes a temperature of 0.0 as ‘default’ (=298.15K). Re-run with a temp of 0.001K and the results should be correct… Chair/boat TS good, animation of the vibrations would have been perfect, but we can see the vibrations anyway 1 imaginary frequency = transition state. Correct, but any ideas why? IRC – good. The 200 step limit is a maximum – if this isn’t needed then the calculation will stop early. This is why methods 1 & 3 give the same result. Activation energies – calculated correctly. Small differences between Table 7/appendix probably because H atoms don’t weigh exactly 1.0 by default (as they do in your inputs for 0K calculations).

Diels Alder: Good introduction to topic, and again clearly laid out. TS – comparison of methods great, and MOs & descriptions all present and correct. Description of vibration pictures does help. IRC & activation energies – good. Perhaps compared with literature if you could find some? Secondary orbital overlap – good explanation of the theory, perhaps the HOMO-10/-19 are a little low to be looking for the overlap – could you see similar MOs (potentially) in the exo? There are also competing steric effects for the endo/exo selectivity, probably a balance between these too.

Overall: A very clearly presented report, with all the relevant results easy to see. Some little mistakes (e.g. with 0K energies) but also some helpful additions, like the activation energies for the Diels Alder reactions. Generally very good and well understood.