Computational Studies Of Mgc4h Isomers

Sinjari, Aland

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https://hdl.handle.net/2142/116821 Copy

Description

Title

Computational Studies Of Mgc4h Isomers

Author(s)

Sinjari, Aland

Contributor(s)

• Thimmakondu, Venkatesan S.
• Ghosal, Subhas
• Roy, Tarun

Issue Date

2022-06-21

Keyword(s)

Mini-symposium: Benchmarking in Spectroscopy

Abstract

Constitutional isomers of MgC$_4$H elemental composition are theoretically investigated in this work using density functional theory at various levels. The linear doublet ($^2\Sigma^+$) isomer, 1-magnesapent-2,4-diyn-1-yl ({\bf 1}), was identified not only in the laboratory but also in the evolved carbon star, IRC+10216. While zero-point vibrational energy corrected relative energies obtained at the ROB3LYP/6-311++G(2d,2p) and RO$\omega$B97XD/6-311++G(2d,2p) levels correctly predict that isomer {\bf 1} is the global minimum geometry, the same obtained with UHF wavefunctions predict that a cyclic isomer, 1-ethynyl-1-$\lambda^3$-magnesacycloprop-2-yne ({\bf 2}), is the global minimum structure. \begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.42]{6375.eps} \end{wrapfigure} Further electronic structure calculations carried out with GGA-functional, such as PBE0-D3 with def-TZVP basis set predict that isomer {\bf 1} is the global minimum irrespective of whether the solutions are based on ROHF or UHF wavefunctions. It is outlined here that the issue of spin-contamination (though under 5 $\%$) becomes a serious one affecting the relative energies dramatically while using hybrid functionals such as B3LYP and $\omega$B97XD in this case.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116821

DOI

https://doi.org/10.15278/isms.2022.TI04

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Copyright 2022 held by the authors

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