Rotationally averaged linear absorption spectra beyond the electric-dipole approximation. (17th January 2017)

• Record Type: Journal Article
• Authors: List, Nanna Holmgaard; Saue, Trond; Norman, Patrick
• Is Part Of: Molecular physics. Volume 115:Number 1/2(2017)
• Page Start: 63
• Page End: 74
• Publication Date: 2017-01-17
• Subjects: Response theory -- multipole-expansion free -- rotational averaging -- Lebedev quadrature -- X-ray absorption; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2016.1187773
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: Based on the recently developed implementation of the full semi-classical field–matter interaction operator, we present a numerically accurate yet efficient scheme to perform rotational averaging of linear absorption spectra beyond the electric-dipole approximation. This allows for a gauge-origin independent determination of UV/vis and X-ray absorption spectra for randomly oriented systems such as multilayers, liquids, and gas phase samples. The approach is illustrated by the determination of spectral intensities of electric-dipole allowed π → π* transitions and electric-dipole forbidden n → π* transitions in the UV–vis region of the spectrum as well as electric-dipole forbidden 1s → 3d transitions in the X-ray region of the spectrum. The employed Lebedev quadrature scheme shows very fast convergence with respect to the number of symmetry-independent quadrature points – in all considered cases, the oscillator strengths for the randomly oriented systems are fully converged with use of only seven quadrature points. Abstract :