Outer-Valence Green''s Function Study on Small Biomolecules
Volume Title: 1
Here, a theoretical study of electronic structures of conformers of vitamin C was studied in the gas phase. Outer-Valence Green's Function (OVGF) methodology employing with 6-311g++(d,p) basis set was used for the calculations. The stable conformers were selected by thermochemistry calculations and the ionization energies were obtained for them. Also, these results have been compared with another ionization method, for example, SAC-CI calculations. The comparison of two spectra shows that OVGF results are in better with experimental data for moieties of vitamin C. So the SAC-CI spectra were shifted along the ionization energy scale to enable the first band in SAC-CI spectrum to match the first band in corresponding OVGF spectrum. Natural Bonding Orbital (NBO) study was performed for analyzing each band of ionization. NBO calculations showed that the first ionization band of vitamin C was related to the electrons of the C=C bond of the ring in the structure of the molecule.