Research

I have been involved in the development and application of computational methods for studying interfacial systems at molecular scales. Here, I describe my current, past and planned future research projects, respectively. Please feel free to contact me regarding any questions or opinions about my research.

Current projects

1.Temperature dependence of wetting behavior

Temperature dependence of wettingWill a drop of liquid spread on a solid surface after increasing temperature? A brief review of literature tells us that the answer is not trivial. It is an interesting scenario where many things – at multiple scales – remain to be understood. Then, there is the challenging design problem: Can we design solid-liquid systems that show the desired thermal response?  The technological implications are many. Think about very small engines, or the development of the ink-jet printing technology. In this project we are employing theoretical and computational methods to study the thermal response of the liquid-on-solid wetting. We are initially using statistical mechanics and molecular simulations to study the temperature dependence of solid-liquid interfacial properties.  In the process we are also evaluating the potential for designing solid surfaces that show the desired thermal response to wetting.  Concurrently, we are also interested in investigating the potential application of the “wetting engines” using thermodynamic analysis.

2. Connecting molecular-scale phenomena to macroscopic properties

Molecular simulation is an important tool to get the molecular-level insights of a particular system. The inferences from simulation studies are routinely drawn by calculating a macroscopic property (like surface tension) on one hand, performing some sort of visual analysis on the other, and relating the two observations. For example, the visual analysis may mean determining the distribution of certain molecular species using the simulation-data. There is a good chance that such an analysis may not provide the actual extent of the role of a particular molecular phenomena to the macroscopic observable. In some cases, a deeper theoretical analysis indicates that a particular molecular-scale phenomena should not affect the concerned macroscopic observable.

In this project we are developing a generic statistical-thermodynamics-based approach to analyze the molecular simulation data. The main objective is to quantify the contribution of a particular class of molecular-scale phenomena to a particular macroscopic observable. The project is inspired by our previous work on molecular solutes at water-vapor interfaces. One can think of the proposed approach as a “functional” microscope that not only allows us to observe a molecular-scale phenomenon, but also illuminates its relationship with a given macroscopic property.

3. Ions at interfaces

The arrangement of ions at water-vapor and water-solid interfaces play important role in natural and artificial processes. We are interested in relating such arrangements to the thermodynamic variables that are relevant for theoretical and experimental studies.

Ion at l-v interfaceIons at water-vapor interface. In this project, we are using molecular simulations to study the propensity of certain ions to concentrate at water-vapor interfaces. Specifically, we want to understand the role of thermal capillary waves, that are characterized by long-ranged correlations of certain quantities along the interface. In order to do this, we are employing concepts from integral equation and capillary wave theories to analyze the data obtained from  molecular simulations. The goal is to approximately isolate the contribution of capillary waves to the solvation free energy of ions and its components. More information will be made available in near future.

ions at s-l interfaceIon-pairing at water-solid interface. In near future, we plan to study the tendency of oppositely charged ions to pair near hydrophobic solid surfaces, and the impact of such phenomenon on macroscopic properties. First, we will understand the stability of different arrangements of two oppositely charged ions at the water-solid interface. Here, we will develop and apply molecular simulation techniques to gather this information in a computationally efficient manner. Next, we will consider hypothetical multicomponent systems containing ion-pairs and free ions as separate chemical species. We then plan to artificially change the proportion of ion-pairs and free ions using advanced simulation techniques and track the variation of macroscopic thermodynamic properties.

Previous projects

I have classified my previous research projects into different subject areas. I find such classification useful in tracking the knowledge gained while working on them. Such an exercise can help me teach the related topics in future. Also, note that the classification may change with time, and some of the past questions may be addressed in detail in my current projects. Please click on the images below to know the details.

Molecular Simulations

Molecular Simulations

Statistical Thermodynamics

Statistical Thermodynamics

Phase Coexistence

Phase Coexistence

Interfacial Phenomena

Interfacial Phenomena

Long-term interests

I am always fascinated by the ability of theoretical models to provide insights into a natural phenomenon by allowing us to tweak the reality. In the long run I am interested in sharing this fascination with other students of interfacial science by developing suitable computational methods. The webpage linked below explains the research strategy that will be used, in cooperation with my present and future colleagues, to achieve this goal. Details about my specific research interests will be provided on request. More information