Inner-shell photoabsorption spectra

Abstract

Based on multi-scattering self-consistent field method, the photoabsorption spectra near C 1s threshold of CH4(near-threshold structure) have been studied with the broken symmetry from To. The most possible geometry of the core excited CH4** is determined as the C3v symmetry; the core excited CH4** molecules have the same bond angle (109.5o) as that of the ground state CH4 and consist of one shorter bond length (1.91 a. u.) and three longer bond lengths (2.04 a. u.). The three longer bond lengths are almost the same as that of the ground state CH4, and the averaged bond length (2.01 a. u.) of core excited CH4** is shorter than that of the ground state CH4(2.06 a. u.).