Using collocation and solutions for a sum-of-product potential to compute vibrational energy levels for general potentials

05 July 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

It is easier to compute a vibrational spectrum when the potential energy surface (PES) is a sum-ofproducts (SOP). Many popular computational methods work only if the PES is a SOP. However, the most accurate PESs are not SOPs. We propose using collocation and solutions of the Schrödinger equation with a SOP PES to compute solutions on a corresponding general PES. This makes it possible to account for coupling and anharmonicity omitted from the SOP PES. We find that correcting energy levels computed on a SOP PES with collocation reduces differences with exact energy levels by about two orders of magnitude.

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