Theoretical and computational studies of clusters, liquids, interfaces and
supercritical fluids using classical and quantum methods.
Some specific research interests:
- Structure and dynamics of molecular solutions in bulk and confined systems
- Chemical reaction dynamics in condensed phases
- Molecular properties of solid-liquid, membrane-liquid, liquid-liquid and liquid-vapour interfaces and hydrogen bonded nanoclusters.
- Structure and dynamics of supercooled and supercritical liquids
- Structure and dynamics of macromolecular solutions
- Classical and quantum simulations of clusters and condensed phases
- Hydrogen bonds and charge defects in associated systems.
A major part of our work has been on the dynamics of electrolyte solutions at finite ion concentrations. We developed a fully molecular theory of ion atmosphere relaxation and it's effects on dynamic response functions of ions and solvent molecules, frequency dependent ion conductivity, dielectric relaxation and solvation dynamics in concentrated electrolyte solutions and also on the dynamics of chemical reactions such as charge transfer and isomerization reactions occurring in solutions at finite ion concentrations. We have also looked at the effects of ions on the single-particle, pair and collective dynamics of solvent molecules and also on the structural and dynamical properties of molecular solutions under supercooled and supercritical conditions by means of classical and ab initio molecular dynamics simulations.
We have worked extensively on the behaviour of molecular liquids at interfaces and in confined environment. We developed a fully nonlinear theory of the structure of pure and mixed dipolar liquids near charged and metal surfaces by using a nonlocal density functional theory. For metal surfaces, the theory is based on a combination of classical and quantum density functional theories for the liquid and metal surfaces, respectively. We have also carried out Monte Carlo simulations of various model systems and have shown that the theory developed by our group predicts the interfacial structure quite accurately. By means of molecular dynamics simulations and analytical theories, we have shown how different the dynamics of molecular relaxation at solid-liquid and liquid-vapour interfaces and in cavity are than that in the bulk phases and to what extent the modifications of the dynamics depend on the nature of the surfaces and on the degree of confinement. We have also shown theoretically how the dielectric constant of a solvent is reduced when it is confined in cavities of nano-dimensions. Subsequently, we extended these studies to liquid-vapour and liquid-liquid interfaces.
The behaviour of complex chemical systems under non-ambient conditions has been another major area of our research work. He have made a detailed molecular-level investigation of the effects of pressure on diffusion of ionic and molecular solutes in supercooled aqueous solutions and correlated the observed diffusion anomalies with changes of hydrogen bond properties on decrease of temperature and increase of pressure. He have also focused on the anomalous size dependence of ion diffusion in aqueous and non-aqueous solutions and showed that the anomaly is enhanced under supercooled or very cold conditions.
Studies of hydrogen bond dynamics in associated liquids constitute a major area of our research in recent years. We have investigated the effects of ions on the dynamics of breaking and structural relaxation of water-water and anion-water hydrogen bonds in aqueous electrolyte solutions by means of classical molecular dynamics. In these studies, the ions and water molecules are modelled by empirical interaction potentials. Very recently, we have gone beyond the use of empirical potentials and have used the technique of Car-Parrinello molecular dynamics to study the relaxation of hydrogen bonds in both aqueous and non-aqueous associated liquids and also to the study of charge defects in aqueous systems in liquid, cluster and confined environments.
Full list of publications