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Entropy and Solvation

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The process of surrounding a solute with solvent is called solvation. It involves evenly distributing the solute within the solvent. The rule of thumb for determining a solvent for a given compound is that like dissolves like. A good solvent has molecular characteristics similar to those of the compound to be dissolved. For example, polar solutions dissolve polar solutes, and apolar solvents dissolve apolar solutes. A polar solvent is a solvent that has a high dielectric constant (ϵ ≥ 15); an...

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Updated: Jun 17, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

A tetrahedral entropy for water.

Pradeep Kumar¹, Sergey V Buldyrev, H Eugene Stanley

¹Center for Studies in Physics and Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA. pradeep.kumar@rockefeller.edu

Proceedings of the National Academy of Sciences of the United States of America

|December 19, 2009

Summary

This summary is machine-generated.

Computer simulations reveal that water

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Area of Science:

Computational chemistry
Statistical mechanics
Physical chemistry

Background:

Understanding the structure and dynamics of water is crucial in various scientific disciplines.
Local tetrahedral order is a key feature influencing water's unique properties.

Purpose of the Study:

To investigate the space-dependent correlation function C(Q)(r) and time-dependent autocorrelation function C(Q)(t) of the local tetrahedral order parameter Q.
To explore the relationship between tetrahedral order, dynamics, and thermodynamics in water.

Main Methods:

Computer simulations of 512 waterlike particles using the TIP5 potential.
Analysis of the local tetrahedral order parameter Q(r,t).

Main Results:

C(Q)(t) exhibits a two-step decay at low temperatures, similar to the self-intermediate scattering function.
Correlation time tau(Q) shows a dynamic crossover at the Widom temperature (T(W)).
Tetrahedral entropy S(Q) contributes significantly to the specific heat maximum at the Widom line.

Conclusions:

The study defines and analyzes tetrahedral entropy S(Q) and its relation to water dynamics.
An analog of the Adam-Gibbs relation is proposed to extract tau(Q) from S(Q).