"Improved Semi-experimental Equilibrium Structure Determination And Theoretical Prediction Of Pyridazine (<i>o</i>-<span Class=""roman"">c</span>_{<span Class=""roman"">4</span>}<span Class=""roman"">h</span>_{<span Class=""roman"">4</span>}<span C"

Owen, Andrew N.

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https://hdl.handle.net/2142/111250 Copy

Description

Title

"Improved Semi-experimental Equilibrium Structure Determination And Theoretical Prediction Of Pyridazine (o-c₄h₄

Author(s)

Owen, Andrew N.

Contributor(s)

• McMahon, Robert J.
• Woods, R. Claude
• Stanton, John F.
• Esselman, Brian J.
• Zdanovskaia, Maria

Issue Date

2021-06-25

Keyword(s)

Structure determination

Abstract

We obtained an improved semi-experimental equilibrium structure ($r_{e}$$^{SE}$) of pyridazine (\textit{o}-\chem{C_4H_4N_2}) by improving the distorted-rotor least-squares fits of previously reported experimental data by incorporating fits of four previously unobserved isotopologues and by using higher level, isotopologue-dependent \textit{ab initio} corrections from CCSD(T)/cc-pCVTZ in the $r_{e}$$^{SE}$ determination. As a result, we improved the determination of the parameters of pyridazine by a factor of two, obtaining $2\sigma$ uncertainties of less than $0.001$ {\AA} and $0.04^{\circ}$ in the bond distances and angles, respectively. Additionally, we have obtained an improved theoretical prediction of the structure by using a CCSD(T)/cc-pCV5Z optimization and applying corrections to account for extrapolation to the complete basis set limit, for effects of electron correlation, for relativistic effects, and for the Born-Oppenheimer approximation. The resulting theoretical structural parameters are almost all within the corresponding uncertainties of the improved $r_{e}$$^{SE}$ parameters. Finally, we analyzed the effect of including additional isotopologues on the $r_{e}$$^{SE}$ structure and extended the analysis for comparison to the minimal set of isotopologues as used in substitution structure determinations.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111250

DOI

10.15278/isms.2021.FK08

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