Predicting Core Level Photoelectron Spectra of Amino Acids Using Density Functional Theory

Abstract

<div>Core level photoelectron spectroscopy is a widely used technique to study amino acids. Interpretation of the individual contributions from functional groups and their local chemical environments to overall spectra requires both high-resolution reference spectra and theoretical insights, for example from density functional theory calculations. This is a particular challenge for crystalline amino acids due to the lack of experimental data and the limitation of previous calculations to gas phase molecules. </div><div>Here, a state of the art multiresolution approach is used for high precision gas phase calculations and to validate core hole pseudopotentials for plane-wave calculations. This powerful combination of complementary numerical techniques provides a framework for accurate ΔSCF calculations for molecules and solids in systematic basis sets. It is used to successfully predict C and O 1<i>s</i> core level spectra of glycine, alanine and serine and identify chemical state contributions to experimental spectra of crystalline amino acids.</div>