Ab initio effective rovibrational hamiltonians for non-rigid molecules via curvilinear VMP2

Changala, Bryan

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https://hdl.handle.net/2142/97159 Copy

Description

Title

Ab initio effective rovibrational hamiltonians for non-rigid molecules via curvilinear VMP2

Author(s)

Changala, Bryan

Contributor(s)

Baraban, Joshua H.

Issue Date

2017-06-20

Keyword(s)

• Large amplitude motions
• Internal rotation

Abstract

Accurate predictions of spectroscopic constants for non-rigid molecules are particularly challenging for textit{ab initio} theory. For all but the smallest systems, ``brute force'' diagonalization of the full rovibrational Hamiltonian is computationally prohibitive, leaving us at the mercy of perturbative approaches. However, standard perturbative techniques, such as second order vibrational perturbation theory (VPT2), are based on the approximation that a molecule makes small amplitude vibrations about a well defined equilibrium structure. Such assumptions are physically inappropriate for non-rigid systems. In this talk, we will describe extensions to curvilinear vibrational M{o}ller-Plesset perturbation theory (VMP2) that account for rotational and rovibrational effects in the molecular Hamiltonian. Through several examples, we will show that this approach provides predictions to nearly microwave accuracy of molecular constants including rotational and centrifugal distortion parameters, Coriolis coupling constants, and anharmonic vibrational and tunneling frequencies.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/97159

DOI

https://doi.org/10.15278/isms.2017.TD02

Copyright and License Information

Copyright 2017 Bryan Changala

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