CONSTRUCTION OF POTENTIAL ENERGY SURFACES FOR THEORETICAL STUDIES OF SPECTROSCOPY AND DYNAMICS

Dawes, Richard

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https://hdl.handle.net/2142/79177 Copy

Description

Title

CONSTRUCTION OF POTENTIAL ENERGY SURFACES FOR THEORETICAL STUDIES OF SPECTROSCOPY AND DYNAMICS

Author(s)

Dawes, Richard

Issue Date

24-Jun-15

Keyword(s)

Plenary

Abstract

Accurate potential energy surfaces (PESs) combined with methods to solve the Schrﾚdinger equation for the nuclei permit the prediction and interpretation of various types of molecular spectra and/or dynamics. Part of this talk describes the development of a PES generator (software code) which uses parallel processing on High-Performance Computing (HPC) clusters to construct PESs automatically. Thousands of ab initio data are computed at geometries chosen by an algorithm and fit to a functional form. This strategy is particularly successful when the electronic structure is robustly convergent (such as vdWs systems composed of two closed-shell monomers). Results for a few of such systems [e.g., (CO)$_{2}$, (NNO)$_{2}$, CO$_{2}$-CS$_{2}$, (OCS)$_{2}$] will be presented. The electronic structure of molecules is difficult to describe continuously across global reactive PESs since it changes qualitatively as bonds are formed and broken along reaction coordinates. I will discuss a high-level ab initio method (GDW-SA-CASSCF/MRCI) designed to allow the electronic wavefunction to smoothly evolve across the PES and provide an accurate and balanced description of the various regions. These methods are combined to study a number of small gas-phased molecules from the areas of atmospheric, combustion and interstellar chemistry including a large variational calculation of all the bound vibrational states of ozone and the photodissociation dynamics of the simplest Criegee intermediate (CH$_{2}$OO).

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79177

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