<br/>With the increasing availability and performance of X-Ray sources for spectroscopy comes a concurrent desire to improve theoretical methods to characterize core excited states. X-Ray/XUV spectroscopy offers elemental and oxidation state specificity, allowing for novel observations such as dynamics along a well defined potential energy surface. Determining such a surface and assigning features in an experimental spectra requires calculating core excitations; a notably difficult task for many <i>ab initio</i> methods. Both core orbitals, which are less than doubly occupied, and valence orbitals, which see an higher effective charge from the core, must be carefully considered. A variety of electronic structure methods, such as NOCIS, ADC, and EOM-CCSD, among others, have been extended to predict core excitation energies with reasonable accuracy. An alternative path worth exploring is Quantum Monte Carlo, which recently has been extended to include explicit orbital relaxations to accurately represent excited state orbitals. We will present our findings on calculating core excited states utilizing excited state specific multi-slater Jastrow orbital optimized wave functions.

State specific quantum Monte Carlo targeting of core excited states

2019 Fall National Meeting

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