Center for Functional Nanomaterials Seminar

Abstract: Near-edge x-ray spectroscopies such as x-ray absorption spectra (XAS) and resonant inelastic x-ray scattering (RIXS) are commonly used to elucidate the local electronic and atomic structure of materials. X-rays provide a bulk-sensitive, element-specific probe that is responsive to bonding, coordination, and charge states. The OCEAN code is a tool for calculating near-edge x-ray spectra (absorption, emission, RIXS, and NRIXS). Building upon a density functional theory foundation, OCEAN solves the Bethe-Salpeter equation to describe the electron-hole pair created by x-ray absorption or scattering. This allows us to predict spectra for a wide range of condensed matter systems wherein the molecular structure is the only free parameter. Today's talk will introduce some of the capabilities of the OCEAN code and walk through the steps necessary to create and run your own calculations. As an example we will look at some recent results of absorption and resonant emission at the nitrogen K edge in ammonium nitrate which highlight both vibrational disorder and many-body self-energy effects.