X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy are nondestructive surface analysis techniques. There are a lot of theoretical tools for the analysis of their results. A very useful methodology to the NEXAFS spectra calculation is the time-dependent density functional theory (TDDFT) in the adiabatic approximation. However, if the standard exchange�correlation functionals are used, the TDDFT calculation yields the values for the core excitation energies that are too low compared with experiment. This malfunctioning is caused by the approximations allowed in description of the exchange interaction within the exchange�correlation functional scheme. To circumvent this drawback in the TDDFT description of NEXAFS spectra, recently the short range corrected (SRC) functionals were formulated by Besley et al. The crux of the SRC method is the separation of Coulomb operator into two components: the short-range component utilizing predominantly the Hartree-Fock exchange, while the long-range component exploits the standard DFT exchange. The focus of our studies is the accurate computation of the XPS spectra by the delta self-consistent field (?SCF) method. Our goal is finding a reliable, accurate, and efficient method for the calculation of XPS chemical shifts in biomolecules. We have reparametrized the short-range corrected (SRC) functional proposed by Besley et al. for the XPS analysis needs. We have established the optimum set of Coulomb attenuation parameters and range separation distances. The mean unsigned errors calculated for CEBEs and chemical shifts were found to reproduce the experimental data within 0.1 eV after the application of the reparametrized SRC methodology. We have concluded that this reparametrized scheme is accurate and reliable for the ?SCF-DFT calculation of CEBEs and chemical shifts in biomolecules.

Reparametrization of short-range corrected functionals for the ?SCF-DFT calculation of core electron binding energies and chemical shifts

248th National Meeting (2014)

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