Abstract
Quantum Chemical Topology (QCT) is used to reveal the dynamics of atom-atom interactions in a liquid. A molecular dynamics simulation was carried out on an ethanol-water liquid mixture at its azeotropic concentration (X ethanol = 0.899), using high-rank multipolar electrostatics. A thousand (ethanol)9-water heterodecamers, respecting the water-ethanol ratio of the azeotropic mixture, were extracted from the simulation. Ab initio electron densities were computed at the B3LYP/6-31+G(d) level for these molecular clusters. A video shows the dynamical behavior of a pattern of bond critical points and atomic interaction lines, fluctuating over 1 ns. A bond critical point distribution revealed the fluctuating behavior of water and ethanol molecules in terms of O-H⋯O, C-H⋯O and H⋯H interactions. Interestingly, the water molecule formed one to six C-H⋯O and one to four O-H⋯O interactions as a proton acceptor. We found that the more localized a dynamical bond critical point distribution, the higher the average electron density at its bond critical points. The formation of multiple C-H⋯O interactions affected the shape of the oxygen basin of the water molecule, which is shown in three dimensions. The hydrogen atoms of water strongly preferred to form H⋯H interactions with ethanol's alkyl hydrogen atoms over its hydroxyl hydrogen. © 2011 the Owner Societies.
Original language | English |
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Pages (from-to) | 7821-7833 |
Number of pages | 12 |
Journal | Physical Chemistry Chemical Physics |
Volume | 13 |
Issue number | 17 |
DOIs | |
Publication status | Published - 7 May 2011 |