Gauging aromatic conjugation and charge delocalization in the aryl silanes Ph_nSiH_4−n (n = 0–4), with silicon K-edge XAS and TDDFT

Abstract

Si K-edge X-ray absorption spectra (XAS) have been measured experimentally and calculated using time-dependent density functional theory (TDDFT) to investigate electronic structure in aryl silanes, PhnSiH4−n (n = 0–4).

On the choice of reference orbitals for linear-response calculations of solution-phase K-edge X-ray absorption spectra

“…17,18 In the context of XAS, orbital relaxation refers to the strong polarizing effect on all orbitals due to removing an electron from a core orbital and is deficient in all varieties of linear-response methods that include only singly-excited configurations in a wave function generated from ground-state reference orbitals. While TDDFT has shown some promise in modeling liquid-phase XAS, very few studies exist on the topic, 5,[19][20][21] and therefore the importance of orbital relaxation and particle-hole interaction errors in the condensed phase are yet to be thoroughly assessed.…”

“…This effect is nearly absent in all varieties of linear-response methods that include only singly-excited configurations in a wave function generated from ground-state reference orbitals. While TDDFT has shown some promise in modeling liquidphase XAS, it has not been intensively studied until recently, 5,[19][20][21][22][23] leaving the importance of orbital relaxation and particle-hole interaction errors in the condensed phase yet to be thoroughly assessed.…”