These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
The Orbital Picture of the First Dipole Hyperpolarizability from Many-Body Response Theory
preprintsubmitted on 02.03.2021, 11:29 and posted on 03.03.2021, 05:49 by Kaushik Nanda, Anna Krylov
We present an approach for obtaining a molecular orbital picture of the first dipole hyperpolarizability from correlated many-body electronic structure methods. Ab initio calculations of β rely on quadratic response theory, which
recasts the sum-over-all-states expression of β into a closed-form expression by calculating a handful of first- and
second-order response states; for resonantly enhanced β , damped response theory is used. These response states are
then used to construct second-order response reduced one-particle density matrices (1PDMs), which, upon visual-
ization in terms of natural orbitals (NOs), facilitate a rigorous and black-box mapping of the underlying electronic
structure with β. We explain the interpretation of different components of the response 1PDMs and the corresponding
NOs within both the undamped and damped response theory framework. We illustrate the utility of this new tool by
deconstructing β for cis-difluoroethene, para-nitroaniline, and hemibonded OH . +H 2 O complex, computed within the
framework of coupled-cluster singles and doubles response theory, in terms of the underlying response 1PDMs and
NOs for a range of frequencies.