NEXAFS spectra of aromatic molecules by plane-wave calculations
Abstract
Near-edge x-ray absorption fine structure (NEXAFS) is a powerful technique which allows one to determine several important properties of organic molecules, both in the gas phase and in the bulk or adsorbed one and especially, by performing angle-dependent measurements with polarized x-rays, to the absolute orientation of molecules. This calls for the association of measured peaks to specific transitions, which can be guided by theory. To this respect, the use of numerically-efficient yet accurate first-principles simulations in determining the spectral features is desirable, aiming at simulating fairly large systems such as molecules interacting with metal/dielectric surfaces. We consider here a technique from the literature to derive effectively the spectrum from density-functional theory, using pseudopotentials and plane wave basis sets, that was mostly applied to bulk systems. The basic aspects to its applicability to molecular systems will be discussed, taking as examples benzene, pentacene, and related molecules and comparing to experimental and theoretical data in the literature with special emphasis on the spectrum dependence on the photon polarization.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2013
- Bibcode:
- 2013APS..MARU43003F