Metastable Autoionizing States of Molecules and Radicals in Highly Energetic Environment
Technical Report,01 Oct 2012,30 Sep 2015
University of Southern California Los Angeles United States
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The main goal was to develop electronic structure methods targeting electronic states that are metastable with respect to electron detachment, to aid computational studies of fundamental chemical processes involving molecules and radicals in highly excited and ionized electronic states. The specific aims are to develop and calibrate complex-scaled equation-of-motion coupled cluster cs-EOM-CC and CAPcomplex absorbing potential augmented EOM-CC methods. We have implemented and benchmarked cs-EOM-CCSD and CAP-augmented EOM-CCSD methods for excitation energies and electron attachment. We investigated the performance of CAP-EOM-CCSD for various molecular shape resonances. By analyzing analytic energy expression, we discovered a simple yet efficient de-perturbative correction that eliminates the unphysical perturbation due to the finite-strength CAP. Our version of CAP-EOM-CCSD has shown robust performance, improved accuracy, and decreased dependence on the CAP onset parameters. We also tested this approach for potential energy curves. Unlike the original versions of CAP methods, our 1st order corrected CAP-EOM-CCSD yields smooth and internally consistent potential energy curves. We extended the methodology to describe properties of resonance states by implementing Dyson orbitals and transition dipole moments. We also applied this methodology to recent experimental results on resonances.
- Physical Chemistry