A state-specific mean field theory for excited states (ESMF) that uses a variational principle to determine energy stationary points was recently developed. Using this theory as a foundation, an excited state analog to second order Møller-Plesset perturbation theory (MP2) was created and showed promising results, with errors on the order of millihatrees when compared to EOM-CC(2,3), however, the scaling of this perturbative method was O(n7). Through the use of internal contraction the computational cost of this method can be decreased to O(n5), allowing access to systems that are not possible to calculate using EOM-CCSD. This method could allow for insight into chemical processes that rely on the formation of excited states to proceed, such as solar energy conversion, and aid in the understanding of charge transfer excitations and Rydberg states. We will present our approach to implementing the O(n5) MP2 method based on the ESMF zeroth order Hamiltonian as well as preliminary results.

Excited state Møller–Plesset perturbation theory

2019 Fall National Meeting

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