Issue 8, 1991

Basis set and electron correlation effects on the internal rotational barrier heights of formamide and acetamide

Abstract

The internal rotational barrier heights of formamide and acetamide were studied by ab initio molecular orbital calculations using several basis sets up to 6-311 G (2d,2p) with electron correlation correction. The calculated barrier heights depended on the basis set used. The calculated barrier heights with the MP3 (Møller–Plesset 3rd order perburbation) electron correlation correction were decreased by the augmentation of polarized functions by as much as 5–6 kcal mol–1. Further augmentation of multiple polarized functions and diffuse functions had little effect on the calculated barrier heights. The calculated barrier heights using polarized basis sets were decreased by the incorporation of electron correlation by as much as 1–2 kcal mol–1 from the values obtained by HF method. The calculated barrier heights of formamide and acetamide using polarized basis sets with electron correlation correction were 14.5–15.4 and 12.5–13.2 kcal mol–1, respectively. Whereas these barrier heights were 1–8 kcal mol–1 lower than the experimental values measured in the liquid phase, the calculated values were close to the barrier heights measured in a polystyrene matrix. Zero point and thermal vibrational energies of formamide were calculated at HF/6-31 G* level. The calculated vibrational energy correction for the barrier height was only –0.75 kcal mol–1.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 2, 1991, 1255-1260

Basis set and electron correlation effects on the internal rotational barrier heights of formamide and acetamide

S. Tsuzuki and K. Tanabe, J. Chem. Soc., Perkin Trans. 2, 1991, 1255 DOI: 10.1039/P29910001255

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements