Free energy of cavity formation in liquid water and hexane

Martine Prévost, Isabel T. Oliveira, Jean-Pierre Kocher, Shoshana J. Wodak

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The difference between the work of forming a cavity in water versus organic solvents is believed to play an important role in making apolar solutes less soluble in water than in these solvents, a property commonly referred to as the hydrophobia effect. In this study, two methods are applied, using molecular dynamics simulations, to compute the free energy of forming spherical cavities in the water and hexane liquids. One, based on the free energy perturbation approach, involves gradually growing into the liquid a soft cavity, by turning on a repulsive potential. The other computes the likelihood of finding a natural cavity in configurational data of neat liquids. In addition, the free energy of cavity formation in the two liquids is evaluated by the scale particle theory. Using all three approaches, we investigate how this free energy is influenced by the different descriptions of the cavity-solvent system: the perturbation method considers soft cavities whereas the statistical approach and scale-particle theory deal with hard sphere cavities. Also the scale-particle theory uses a simplified representation of the solvent while the computational procedures use an atomic description. The results of the perturbation approach show that it is more costly to accommodate a cavity of molecular size in water than in hexane, in agreement with previous evaluations, based on the statistical approach. In hexane, we obtain a rather similar cavity size dependence of the free energy computed with the two simulation methods. In principle, this should also be the case for water. We find, however, significantly higher free energy values in water with the statistical method than with the perturbation approach. This result is confirmed by an analysis of the structure of water around the cavities. Ways of bringing the two calculations to converge to the same result are discussed.

Original languageEnglish (US)
Pages (from-to)2738-2743
Number of pages6
JournalJournal of Physical Chemistry
Volume100
Issue number7
StatePublished - Feb 15 1996
Externally publishedYes

Fingerprint

Hexanes
Hexane
Free energy
free energy
cavities
Water
Liquids
liquids
water
particle theory
perturbation
Organic solvents
Molecular dynamics
Statistical methods
Computer simulation
solutes
simulation
molecular dynamics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Prévost, M., Oliveira, I. T., Kocher, J-P., & Wodak, S. J. (1996). Free energy of cavity formation in liquid water and hexane. Journal of Physical Chemistry, 100(7), 2738-2743.

Free energy of cavity formation in liquid water and hexane. / Prévost, Martine; Oliveira, Isabel T.; Kocher, Jean-Pierre; Wodak, Shoshana J.

In: Journal of Physical Chemistry, Vol. 100, No. 7, 15.02.1996, p. 2738-2743.

Research output: Contribution to journalArticle

Prévost, M, Oliveira, IT, Kocher, J-P & Wodak, SJ 1996, 'Free energy of cavity formation in liquid water and hexane', Journal of Physical Chemistry, vol. 100, no. 7, pp. 2738-2743.
Prévost M, Oliveira IT, Kocher J-P, Wodak SJ. Free energy of cavity formation in liquid water and hexane. Journal of Physical Chemistry. 1996 Feb 15;100(7):2738-2743.
Prévost, Martine ; Oliveira, Isabel T. ; Kocher, Jean-Pierre ; Wodak, Shoshana J. / Free energy of cavity formation in liquid water and hexane. In: Journal of Physical Chemistry. 1996 ; Vol. 100, No. 7. pp. 2738-2743.
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