Hydrophobic solvation and liquid water: A theoretical investigation using thermodynamic perturbation and integral equations theory

In this paper we have investigated the thermodynamic and structural properties of liquid water and hydrophobic solvation using thermodynamic perturbation theory (TPT) and integral equation theory (IET). In the study a three-dimensional Mercedes-Benz (3D MB) water model was used. 3D MB model is a coarse-grained representation of water, designed to capture essential properties of hydrogen bonding and the tetrahedral structure of liquid water. This model provides a simplified yet effective approach to studying water's unique thermodynamic and structural properties. Our study explores both pure water and the solvation of nonpolar solutes and we have found that the 3D MB model effectively captures key aspects of hydrophobic solvation, including the temperature dependence of solvation thermodynamics for noble gases. These results show qualitative agreement with experimental data, validating the model's ability to combine computational efficiency with physical accuracy. Using Kirkwood-Buff theory, we provide deeper insights into solvation dynamics and local structural changes in water induced by nonpolar solutes. This work shows that the 3D MB model is a great option for studying molecular-scale phenomena in water and hydrophobic solvation. It also establishes a foundation for extending the model to more complex systems, such as polar solutes, confined environments, and dynamic properties like diffusion and transport. The approach presented here offers broad applications across biophysics, materials science, and the chemical sciences. • 3D Mercedes-Benz water model was used to study hydrophobic solvation properties of noble gases. • TPT and IET provide insights into solvation thermodynamics and water structure. • Establishes a foundation for extending the model to complex systems, including polar solutes and confined environments.