Nondynamical correlation effects in multidimensional potential energy curves of prototypical hydrocarbons

Title
Nondynamical correlation effects in multidimensional potential energy curves of prototypical hydrocarbons
Publication Date
2025-01-15
Author(s)
Karton, Amir
( author )
OrcID: https://orcid.org/0000-0002-7981-508X
Email: akarton@une.edu.au
UNE Id une-id:akarton
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Elsevier BV
Place of publication
The Netherlands
DOI
10.1016/j.chemphys.2024.112498
UNE publication id
une:1959.11/63781
Abstract

We demonstrate that simultaneously stretching all bonds in a molecule by small increments provides a systematic approach to gradually increasing its multireference character. We show this for four hydrocarbons — methane, ethane, ethylene, and acetylene — each representing a progressively more complex electronic structure. The T1, D1, and %TAE[(T)] multireference diagnostics increase as all the bonds are stretched simultaneously. The post-CCSD(T) correlation components of the total atomization energy (TAE) up to CCSDTQ systematically increase as the bonds are stretched. The extent of the increase in the multireference character correlates with the complexity of the electronic structure in the order methane → ethane → ethylene → acetylene. The CCSDTQ/CBS multidimensional potential energy curves serve as benchmarks for assessing the performance of DFT methods for strong correlation effects. The conventional DFT methods B97-D, TPSS, and TPSSh and double-hybrid DFT methods are more robust toward multireference effects.

Link
Citation
Chemical Physics, v.589, p. 1-10
ISSN
1873-4421
0301-0104
Start page
1
End page
10

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