CALCULATION OF RESONANCES IN NEAR-EDGE X-RAY ABSORPTION FINE STRUCTURE SPECTRA USING THE CONSTANT CHEMICAL POTENTIAL LOCAL DENSITY APPROXIMATION METHOD

摘要

Known prescriptions for the implementation of exchange and correlation potentials fail to reproduce the near-edge X-ray absorption fine structure (NEXAFS) spectrum for a test case of a gas-phase acetylene molecule using computer simulations. A new constant chemical potential-local density approximation (CCP-LDA) calculation method has been developed which ensures the constancy of the chemical potential throughout the molecule for which the calculation is performed within the framework of the local density approximation. A Hedin-Lundqvist potential is used to represent the exchange and correlation potential of the excited state. This method provides excellent agreement between theory and experiment for a range of small gas-phase molecules including acetylene, carbon monoxide, nitrogen and oxygen. References: 17