The research spans systems ranging from small clusters and molecules to extended bulk materials, with particular interest in problems connected to catalysis, photovoltaics, thermoelectrics, and related energy applications. Because these problems often involve multiple length and time scales, we use a combination of computational approaches including DFT, time-dependent DFT, molecular dynamics, NEB, kinetic Monte Carlo simulations and machine learning.
Thermoelectric materials are promising for direct heat-to-electricity conversion, but improving their performance requires a microscopic understanding of transport (electrical and thermal) and scattering processes. In our group, we use first-principles calculations to study thermoelectric behavior in copper chalcogenides, layered materials, and related systems, with emphasis on doping, heterostructure design, and electron-phonon coupling. This work also includes computational and collaborative experimental studies on half-Heusler alloys, particularly high-entropy systems, aimed at understanding measured trends and guiding the design of improved thermoelectric materials.
Additionally we are also developing methods to speed up computation of transport properties in complex high entropy systems by coupling first principles DFT calculations with machine learning interatomic potentials and surrogate models.
Catalysis is a major focus of our group, particularly in the areas of heterogeneous catalysis and related problems in photo- and electro-catalysis. We use first-principles and atomistic simulations to study how bonding, electronic structure, adsorption, and reaction pathways at surfaces and interfaces govern catalytic activity and selectivity in systems relevant to CO oxidation, selective hydrogenation, hydrogen production, carbon dioxide and methane capture and reduction, and water splitting. Since this research is closely tied to practical applications, it is also strengthened by active collaborations with experimentalists at IISER Pune and outside, allowing theory and computation to contribute directly to the interpretation of measurements and the design of improved catalytic materials.
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.
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.