A theoretical study of liquid alcohols using averaged solvent electrostatic potentials obtained from molecular dynamics simulations:: Methanol, ethanol and propanol

We applied a quantum mechanics/molecular mechanics method that makes use of the mean field approximation to study the polarization of several alcohols in the liquid phase. The method is based on the calculation of the averaged solvent electrostatic potential from molecular dynamics data. Because of the reduced number of quantum calculations that our approximation involves, it permits the use of flexible basis sets. the consideration of the electron correlation and the solvent and solute polarization. We found that the molecules studied undergo strong polarization when they pass from the gas to the liquid phase. From this point of view, the polarization methanol displays a behavior lightly different from ethanol and propanol. The vaporization energies are very well reproduced especially when the correlation energy is included. The differences with the experimental values are less than 3% in the three systems studied. Finally, we consider the effect on the thermodynamics and the structure of the solution of the choice of the Lennard-Jones parameters. (C) 2002 American Institute of Physics.