I used one kind of POMs as my catalyst and bombinating it with a support (Fe3O4) to selective oxidize organic compounds in the presence of H2O2. Now my work almost finished, this ternary system (POMs/Fe3O4/H2O2) works good. The oxidation efficiency increases a lot. I also did a cyclic voltammetry experiment, which shows that the current is much higher in this ternary system comparing with POMs/H2O2 and Fe3O4/H2O2. but the electron transfer pathway from substrate to the H2O2 is not clear now. I want to know if the electron from substrate transfer first to the POMs then to the Fe3O4 and in the end to the H2O2. SO I am wondering if I can use DFT calculation to prove this process.
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DFT calculation on a MOLECULE/ NANOCLUSTER using ...
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Hi Peng,
I think you can.
You should do a charge density difference analysis on your DFT calculations. This analysis performs Pi(AB) - Pi(A) - Pi(B), where Pi(A) is the charge density of molecule A obtained from DFT, and Pi(B), and Pi(AB) are the charge densities of molecule B and AB respectively - also from DFT. From this analysis, you can see the net charge transfer that occurs between molecule A and B, and even reveal which orbitals are involved in the charge transfer event.
Alternatively you can also do Bader analysis (http://theory.cm.utexas.edu/henkelman/code/bader/) for A, B and AB, and compare the net charge on molecule A and B when they are paired as AB. From this, you can check if the net charge transfer is from molecule A to B - or from B to A.
As for DFT codes, ORCA could do the job (but I am sure other codes will do fine). ORCA is free. Some pointer: https://sites.google.com/site/orcainputlibrary/home
I guess you could do an IRC calculation to get the transition state which links the reactants and the products. It is also a good way to identify a reaction intermediate that you haven't thought about. You'll need to optimize all the molecules involved in the reaction before carrying out the IRC calculation using Gaussian. It's actually not easy to do and might take a while to attain a transition state that links the reactants and the desired product. You have to keep changing the orientation of the reactants on Gaussview after every calculation. Although I'm still new in this field but recommend this method.
Thanks
It seems that you are not accustomed to DFT. I fear that the previous answers are relatively too sophisticated to be understood by a non specialist.
1 - POMs are complex systems, do you have a precise structure?
2 - Fe3O4 is a solid, the solid surface is involved in your system. This needs a model surface.
3 - You work probably in a liquid phase, H2O?, the solvent effect should accounted for.
I think the best is to discuss and collaborate with an experienced theoretician.
Good luck.
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