Research
In our group we use different computational tools like density functional theory (DFT), time-dependent DFT, molecular dynamics (Born-Oppenheimer, Path-Integral), Kinetic Monte Carlo (KMC), nudged elastic band (NEB), etc. for in silico design of materials or to understand experimental results. Following are some examples of problems of recent interests:
Nuclear Quantum Effects (NQE):
Since the mass of nuclei is much heavier than that of electrons, for most practical purposes nuclei are treated as classical particles. However, for certain light nuclei like Hydrogen and sometimes also in certain heavy nuclei the quantum nature of the nuclei is manifested, primarily through zero point motion of the nuclei and tunneling. For example in H-bonded systems where light protons are involved it is now well established that the delocalization of the proton significantly softens the vibrational modes of a H-bonded system that results in anomalous properties. In our group we are interested in studying these NQE's in both molecules in presence of solvent as well as in organic solids. In particular we are studying ellipticine in polar solvents and molecular crystals of terepthalic acid. In both the cases H-bonding significantly affect there properties. To achieve our goals we use state of the art path-integral molecular dynamics simulations.
Catalysis:
Our group is primarily interested in heterogeneous catalysis. We study several industrially important chemical reactions like CO oxidation, selective hydrogenation of acetylene to ethylene, hydrogen production, carbon dioxide capture and reduction, water splitting, etc. The catalysts we use are typically metal surfaces or clusters supported on oxides and carbides. Apart from trying to understand why a certain material acts as a good catalyst for a particular reaction, we also use this knowledge for rational design catalysts. To achieve our goals, we use DFT based calculations coupled with NEB and KMC.
Thermoelectrics:
With the reduction of fossil fuels and the effect of global warming, there is an increasing demand for clean and green energy. One way to meet this demand is to minimize the loss of energy in the form of heat. A thermoelectric material can be used to absorb this heat and convert it to electrical energy. A property of a thermoelectric material depends on electrical conductivity, thermal conductivity (electronic and lattice contribution) and the Seebeck coefficient. Presently the thermoelectric materials that are commercially used don't have the desired efficiency. Hence there are efforts to discover new materials that can give better efficiency. However, the challenge is that the above mentioned material properties are interdependent in an inverse way that makes tuning of this properties difficult. In our group we are interested in materials with moderate band gap and low lattice thermal conductivity to explore the possibility of using them as thermoelectric materials. Further we also try to tune the different properties by doping, etc. so that we can improve their thermoelectric properties.
Physics and Chemistry of layered materials:
Layered materials like graphene, hexagonal boron nitride (hBN), MXene, transition metal dichalcogenides posses several interesting properties that makes them plausible candidates for several applications. The research efforts in our group in this area are centered around (i) tuning these interesting properties by chemical functionalization, doping, etc. and (ii) how the properties are modified when these materials interact with the substrate. In particular, we have studied how the band gap can be opened and tuned by controlled hydrogenation of a graphene sheet, how properties of hBN and graphene (pristine and hydrogenated) are altered on Ni or Co substrates, effect of Mn-doping in GaSe, etc.