Currently, I am working on sugar conversion reaction (sugar-metal complex) using different transition metals [for example first and second row 'd' block elements]. Based on the activation barrier for the rate limiting step one can predict the good catalyst. But, apart from this, what kind of calculations will help me explain the properties of these transition metals. I have done NBO and NPA analysis but the results are almost similar and comparable with most of the elements.
Can anyone explain the catalytic behaviour of different transition metals using DFT?
You can have a look at the Activation Strain Model by Bickelhaupt. Essentially it involves applying the well established energy decomposition analysis (EDA, or ETS) along a reaction path.
http://pubs.rsc.org/en/Content/ArticleLanding/2010/OB/b926828f#!divAbstract
Review: http://pubs.rsc.org/en/Content/ArticleLanding/2014/CS/c4cs00055b#!divAbstract
A nice application to Pd catalysis: http://www.nature.com/nchem/journal/v2/n5/abs/nchem.614.html
You can also combine with NOCV, (ETS-NOCV, or EDA-NOCV) to get further insight in orbital interactions, especially for reactions where there is no symmetry.
In addition to above answer, M06 single point energy calculations from mPW1PW91 geometries will give you enough precise energy data, probably.
These methods will give you internal energies. But I am curious, how would you add in the rest of the effects? Relativistic effects for transition metals, particularly involving spin, seem to be critical to get some rates correct (not to mention having accurate vibrational data to properly model the barrier crossover). Everyone seems to forget about spin orbit coupling until it takes you out for a spin.
Have a look at some recent papers by Jeremy Harvey combining his minimum energy crossing point method with spin orbit coupling in ADF.