Theoretical Approximations to X-ray Absorption Spectroscopy of Liquid Water and Ice
2010 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 177, no 2-3, 135-157 p.Article in journal (Refereed) Published
We review methods to compute x-ray absorption spectra (XAS) with special focus on the transition potential approach of Triguero et al. [Phys. Rev. B 58, 8097 (1998)] and its application to calculations on water in condensed phase. We discuss the absolute energy scale, functional dependence, broadening versus sampling of intra- and intermolecular vibrational modes, treatment of the continuum, cluster size convergence as well as compare with periodic calculations and with experiment; periodic and cluster model calculations are found to agree very closely in the relevant near-edge region although neither reproduces the pre-edge and main-edge features in the experimental spectra of thin ice films. The real space grid representation of the wave function in the periodic calculations allows a more extended energy range to be described and we find satisfactory agreement with experiment for higher energy continuum resonances. Two proposed alternative approaches using either the potential from a full core-hole (FCH) or the full core-hole with an excited electron in the lowest state (XCH) are shown to lead to spectra that deviate significantly from experiment.
Place, publisher, year, edition, pages
2010. Vol. 177, no 2-3, 135-157 p.
X-ray absorption spectroscopy; DFT; NEXAFS; Water structure; Transition-potential
IdentifiersURN: urn:nbn:se:su:diva-31447DOI: 10.1016/j.elspec.2010.02.004ISI: 000277949100007OAI: oai:DiVA.org:su-31447DiVA: diva2:277036