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

Abstract

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.

Analytical theory of the hydrophobic effect of solutes in water

“…There exist also many other waterlike models that were used for treating hydrophbic effect. Core softened [29] or Jagla fluids [30] possess waterlike structural, dynamic, and thermodynamic anomalies, and these fluids also display waterlike solvation thermodynamics. Another aspect of structure-based coarse graining relies on matching the pair correlation functions of a reference (atomistic) and coarse-grained system [31,32].…”

Properties of a soft-core model of methanol: An integral equation theory and computer simulation study

“…Recently, it has been shown that many structural, thermodynamic, and dynamic properties of water can be reproduced using soft-core spherically symmetrical potentials [7][8][9][10] although certain tradeoffs are necessary due to the transferability issue. 11,12 Angular dependence of hydrogen bonding is necessarily forgone and compensated for with two characteristic lengths that these models must have.…”

Density and structural anomalies in soft-repulsive dimeric fluids

“…After these preliminary works, a large variety of investigations has been carried out more recently to investigate the peculiar physical properties of CS potentials: more specifically, attention has been paid to thermodynamic anomalies of the Hemmer-Stell potential 18,19 and of the Jagla potential [20][21][22] , as well as to liquid-liquid phase transition [23][24][25][26][27][28][29] and waterlike anomalies in CS potentials [30][31][32][33][34][35][36][37] . Also, CS potentials have been adopted to simulate, in a coarse-grain approach, the phase behaviour of water 38 and alcohols 39,40 .…”