I have been running the FEFF to simulate for XANES spectra for the cobalamins (Vitamin B12 cofactors). The issue of interest is between three compounds - Methylcobalamin (Me-Cbl), Cyanocobalamin (CN-Cbl) and Hydroxocobalamin (OH-Cbl). 

Experimentally, Me-Cbl is supposed to the most reduced (in terms of the energy of onset of the rising absorption edge). OH-Cbl and CN-Cbl are supposed to be oxidized wrt Me-Cbl. (The official oxidation state of Cobalt for all the above three systems is +3). 

However, the simulations do no reflect this and it consistently seems to predict a reduced absorption edge for both OH-Cbl and CN-Cbl, in comparison to Me-Cbl. 

I checked the literature to confirm that the molecular coordinates that we are using as input (obtained after structure optimization using DFT - Gaussian09) is consistent with prior literature. 

I am wondering if there is anything related to FEFF that I miss understanding, to note why this is occurring. I am attaching the input files for the three models (these are all truncated to reduce the computational expense on DFT optimization) and the experimental and FEFF simulated spectra that I had obtained.

Any help in understanding this seeming discrepancy is much appreciated.

Thanking you,

Ganesh