University of Illinois Urbana-Champaign

Evaluating VPT2 schemes for accurate automated thermochemistry and spectroscopy for non-covalent systems

Welch, Bradley

Content Files
1472404.pptx
4012.pdf

Permalink

https://hdl.handle.net/2142/104435

Description

Title
Evaluating VPT2 schemes for accurate automated thermochemistry and spectroscopy for non-covalent systems
Author(s)
Welch, Bradley
Contributor(s)
  • Bross, David H.
  • Ruscic, Branko
  • Quintas Sánchez, Ernesto
  • Dawes, Richard
Issue Date
2019-06-19
Keyword(s)
  • Electronic structure
  • Potential energy surfaces
Date of Ingest
  • 2019-07-15T22:16:55Z
  • 2020-01-25T19:31:53Z
Abstract
High level computational thermochemical protocols take an additive approach to computing the total energy of a molecular system. For small systems, components related to the electronic structure can be systematically converged using methods such as coupled-cluster theory at the complete basis limit. The vibrational level pattern (and at 0 K the zero-point energy, ZPE) yields a relatively large contribution and is thus a possible source of significant error. An inaccurate ZPE leads to poor quantities such as enthalpies of formation and hence interpretations in kinetics and dynamics. As a result an accurate determination of this one term is critical and the focus of this talk. Accurate anharmonic models such as VPT2 and VCI exist for semi-rigid molecules in the gas phase. Non-covalent systems are also of importance in a wide range of areas. The VPT2 model has not been applied as widely to non-covalent systems and questions remain as to its general applicability. Here, a screening of low-cost implementations of VPT2 calculations were performed for a series of vdW systems as large as Benzene-Ar. The screening was done with an automated thermochemical protocol. Comparisons are made with full-dimensional variational calculations using global potential energy surfaces, and to experimental data where available.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Permalink
http://hdl.handle.net/2142/104435
DOI
https://doi.org/10.15278/isms.2019.WD05
Copyright and License Information
Copyright 2019 Bradley Welch

Owning Collections

Abstracts & Presentations - 2019 International Symposium on Molecular Spectroscopy PRIMARY