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The Pole Structure of the Dynamical Polarizability Tensor in Equation-of-Motion Coupled-Cluster Theory

submitted on 26.08.2018 and posted on 27.08.2018 by Kaushik Nanda, Anna Krylov, Jürgen Gauss
In this Letter, we investigate the pole structure of dynamical polarizabilities computed within the equation-of-motion coupled-cluster (EOM-CC) theory. We show, both theoretically and numerically, that approximate EOM-CC schemes such as, for example, the EOM-CC singles and doubles (EOM-CCSD) model exhibit an incorrect pole structure in which the poles that reflect the excitations from the target state (i.e., the EOM-CC state) are supplemented by artificial poles due to excitations from the coupled-cluster (CC) reference state. These artificial poles can be avoided
by skipping the amplitude response and reverting to a sum-over-states formulation. While numerical results are generally in favor of such a solution, its major drawback
is that this scheme violates size extensivity.


Email Address of Submitting Author


University of Southern California


United States

ORCID For Submitting Author


Declaration of Conflict of Interest