Aqueous solvation of n-methylacetamide conformers: Comparison of simulations and integral equation theories

Hsiang Ai Yu, B. Montgomery Pettitt, Bernard Pettitt

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Abstract

The aqueous solvation thermodynamics of cis- and trans-N-methylacetamide is studied by integral equation theories and molecular dynamics simulations and compared with Monte Carlo (Jorgensen, W. L.; Gao, J. J. Am. Chem. Soc. 1988, 110, 4212). Although the hypernetted chain (HNC) approximation is generally for polar system, the solvation free energy the fluctuation from the fluctuation (GF) approximation gives much better absolute solvation thermodynamics. With the atomic for the two conformers, the difference in energy the cis and trans conformers equals 1-2 kcal/mol from the HNC and GF approximation, in approximate agreement with the value of 2.2 kcal/mol from a Monte Carlo simulation with very similar parameters. The simpler superposition approximation introduced by Pettitt and Karplus (Chem. Phys. Lett. 1985, 121, 194) gives results for the relative solvation thermodynamics (cis versus trans conformers) that compare well with the more exact integral equation theories.

Original languageEnglish (US)
Pages (from-to)2425-2434
Number of pages10
JournalJournal of the American Chemical Society
Volume113
Issue number7
StatePublished - 1991
Externally publishedYes

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ASJC Scopus subject areas

  • Chemistry(all)

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