Talk:Mod:aw010288

Aled, please read these comments, a considerable amount of time and effort has been spent in examining your labs and writing detailed comments in order to provide you with a good level of carefully evaluated and balanced feedback.

Part1 BH3 Clear explanation of all your calculations. Good vibrational analysis. You could have included more analysis of the MO orbitals – compared qualitative and quantitative. NH3 Good discussion and analysis of what is happening in the calculation. For an extra mark you could have discussed the inversion mechanism in more detail. TM You have identified all the correct information and relevant literature values but you needed to discuss it in a bit more detail. The geometries of the two isomers could have been compared to each other and also with the literature values when the methyls are substituted for phenyl. You should also have discussed the relative energies, and reasons for the differences, in more detail. No D-space (-0.5)

Mini-project Pseudo-potentials should really only be employed when there are second row elements, for first row you should include all the electrons. Only when this is too expensive or relatavisitic effects are important do we use pseudo-potentials.

Do you think is is useful to report your energies to 0.0000001 kJ/mol, do you think that your calculations are accurate to this level? I hope your answer is no. Don't forget that the value you report your results as tells the reader something about the accuracy. In general the B3LYP method is not more accurate than 5kJ/mol and in terms of computed energy differences we don't go further than 0.01 kJ/mol. You also have a similar problem with the bond distances ... the computer is not accurate to 0.00001 Å, it just reports numbers, you have to be aware of what is sensible. Your description of the bonding is very old school, modern MO theory has a very different perspective and if you had looked at the MOs for this system you could have presented a very different picture of the bonding. Nevertheless the bond is weaker leading to a lower barrier to rotation, which you have not discussed.

Out of 6 days on this module, two were assigned to the mini project, this gives you an indication of the volume of work expected, your contribution falls short in this respect. There are no links to D-space files and no explanation of any problems encountered in this respect.