The hydrophobic effect in a simple isotropic water-like model: Monte Carlo study

Journal Article · Mon Apr 14 04:00:00 EDT 2014 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4870514· OSTI ID:22253180

Huš, Matej; Urbic, Tomaz ^[1]

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1. Chair of Physical Chemistry, Department of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia)

Using Monte Carlo computer simulations, we show that a simple isotropic water-like model with two characteristic lengths can reproduce the hydrophobic effect and the solvation properties of small and large non-polar solutes. Influence of temperature, pressure, and solute size on the thermodynamic properties of apolar solute solvation in a water model was systematically studied, showing two different solvation regimes. Small particles can fit into the cavities around the solvent particles, inducing additional order in the system and lowering the overall entropy. Large particles force the solvent to disrupt their network, increasing the entropy of the system. At low temperatures, the ordering effect of small solutes is very pronounced. Above the cross-over temperature, which strongly depends on the solute size, the entropy change becomes strictly positive. Pressure dependence was also investigated, showing a “cross-over pressure” where the entropy and enthalpy of solvation are the lowest. These results suggest two fundamentally different solvation mechanisms, as observed experimentally in water and computationally in various water-like models.

• OSTI ID: 22253180
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 14 Vol. 140; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COMPUTERIZED SIMULATION
ENTHALPY
ENTROPY
MONTE CARLO METHOD
PARTICLES
PRESSURE DEPENDENCE
SOLUTES
SOLVATION
SOLVENTS
TEMPERATURE DEPENDENCE