Investigation of the structure of ethanol-water mixtures by molecular dynamics simulation I: Analyses concerning the hydrogen-bonded pairs

Orsolya Gereben, László Pusztai

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Series of molecular dynamics simulations for ethanol-water mixtures with 20-80 mol % ethanol content, pure ethanol, and water were performed. In each mixture, for ethanol the OPLS force field was used, combined with three different water force fields, the SPC/E, the TIP4P-2005, and the SWM4-DP. Water potential models were distinguished on the basis of deviations between calculated and measured total scattering X-ray structure factors aided by ethanol-water pair binding energy comparison. No single water force field could provide the best agreement with experimental data at all concentrations: at the ethanol content of 80% the SWM-DP, for 60 mol % the SWM4-DP and the TIP4P-2005, whereas for the 40 and 20 mol % mixtures TIP4P-2005 water force field provided the closest match. Coordination numbers and hydrogen bonds/molecule values were calculated, revealing that the oxygen-oxygen first coordination numbers strongly overestimate the average number of hydrogen bonds/molecule. The center-of-molecule distributions indicate that the ethanol-ethanol first coordination sphere expands with increasing water concentration while the size of the first water-water coordination sphere does not change. Various two and three-dimensional distributions were calculated that reveal the differences between simulations with different water force fields. Detailed conformational analyses of the hydrogen-bonded pairs were performed; drawings of the characteristic molecular arrangements are provided.

Original languageEnglish
Pages (from-to)3070-3084
Number of pages15
JournalJournal of Physical Chemistry B
Volume119
Issue number7
DOIs
Publication statusPublished - Jan 16 2015

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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