On the Relationship between Mo K-Edge Energies and DFT Computed Partial Charges
Partial charges in dense materials can be either derived from spectroscopic experiments or computed by quantum chemistry calculations. X-ray absorption near-edge spectroscopy (XANES) energies measured for several Mo-containing materials were correlated with charges computed by two density functional theory (DFT)-based charge assignment methods, namely, the Bader and density derived electrostatic and chemical (DDEC) methods. Our results indicated that DDEC charges correlate better with XANES energies than Bader charges and that both of these methods give far better results than using formal oxidation states. We show that the linear relation between DDEC charges and XANES energies can be used in characterizing the degree of reduction in supported catalyst samples.