All Research Activities

The links on the left list the gist of the latest research activities undertaken out at our section. Contact us for further information.

Radiation damage studies in metals exposed to prolonged nuclear radiation

This work deals with the understanding and computational modeling of phenomenon occurring in core materials of nuclear reactor. We have chosen Fe and Fe-Cr based alloys for this purpose. The aim is to model the material behavior starting from initiation of point defects by nuclear irradiation in these materials, the interactions among the defects produced, formation of voids, swelling of materials etc. These processes occur in different length as well as different time scales. To treat such complex processes theoretically and computationally we need to employ combination of density functional theory, molecular dynamics, kinetic Monte-Carlo and Rate theory approach for different scales. A methodology using classical molecular dynamics (MD) for studying cascade simulation in model systems with existing potentials is developed along with code for pattern recognition of the defect structures in displacement cascades. Since the reliability of a classical molecular dynamics calculation entirely depends on the potential, development of an empirical potential for such model systems is also being pursued.

For more info, contact: Prithwish or Valsakumar.

Transport property calculations using molecular dynamics

Transport properties calculation using molecular dynmics

Transport properties of fluids, like viscosity and diffusion coefficients are computed using molecular dynamics. Expertize is obtained in computing tranpsort properties for model systems using various equilibrium and non-equilibrium methods. A relatively lesser known method for calculating transport properties, called the “reverse nonequilibrium molecular dynamucs” is being tested with respect to its limitations and applicability for simulating viscosity of realisitic systems. Variation of viscosity under various external settings like temperature, pressure and density for realistic systems is currently being studies by this reverse non-equilibrium molecular dynamics method.

For more info, contact: Gururaj or Valsakumar

Ab-initio studies on nanoscale systems

Ab-initio electronic structure calculations on Fe-Co bilayers, super lattices and nanowires were carried out. The studies include DFT calculations of  structure, energetics, and magnetic properties of bilayers and super lattices. The influence of interface mixing on the physical properties compared to a sharp interface is looked at. FexCo(1-x) alloy nanowires  with different values of x in the bcc-(110) orientation  showed nearly half metallic character,  and such systems found application in spintronic devices.   Studies on the  electronic transport properties of nanowires and tunnel junctions using density functional theory combined with non equilibrium green function formalism are currently going on.

Statistical Mechanics of Small Systems

Recent years have seen theoreticians re-raise the foundational questions on applicability of the ideas of statistical mechanics for  nanoscaled systems. These developments have been fuelled by the availability of unprecedented levels of computing power and recent technological advances in the controlled fabrication of nanometer sized objects and physical measurements at these length scales. Ultra-high resolution measurements have revealed some surprising results at variance with bulk properties. Since macroscopic behaviour is well-ratified by equilibrium thermodynamic predictions, this raises questions about the validity thermodynamic principles (equilibrium and nonequilibrium) for the case of small systems. Although there are a few quantitative results available for statistical mechanics of small systems like the fluctuation theorems, the full import of these results and their experimental and computational demonstration is yet to be carried out in all its generality. With significant computing power that is available at our division, we at TSS are trying to demonstrate the applicability and limitations of these theorems as they are applied in molecular dynamic simulations. At this point, we are trying to write a molecular dynamics code that is specifically tailored to function as a testbed for the results of fluctuation theorems and work theorems.

For more info, contact: Valsakumar or Raghavan or Gururaj.

Band Structure Calculations

TSS can claim to have a considerable expertise in performing band structure calculations. Calculations are carried out as an computational verification of result obtained by our experimental colleagues at the group or to propose a theoretical understanding of an experimental result. Calculations are carried out particularly for explaining low temperature experiments, high pressure experiments etc. To give a specific example, a series of band structure calculations were done to provide a comprehensive understanding of the normal and superconducting states of the superconducting compound MgCNi3. The calculations showed that two conduction bands cross the Fermi surface. The analysis based on this observation provided a rationale for understanding the observed unusual temperature dependence of both the normal state resistivity and the Hall coefficient. It was argued that normal state conduction is essentially due to light electrons, whereas, superconductivity may be due to heavy holes.

For more info, contact: Valsakumar.

Quantum entanglement in multipartite systems

Work on quantum entanglement has emerged as a major research area for Theoretical Studies Section. Research is being pursued in understanding and quantifying the entanglment particularly for multipartite quantum systems. Efforts are also made in understanding the decoherence mechanism of qubits coupled with the environment.

For more info, contact: Raghavan or Sivakumar or Kanmani.

Band Structure Calculations

TSS can claim to have a considerable expertise in performing band structure calculations. Calculations are carried out as an computational verification of result obtained by our experimental colleagues at the group or to propose a theoretical understanding of an experimental result.

Entanglement in Bipartite Generalized Coherent States

Quantum entanglement in multipartite systems

Work on quantum entanglement has emerged as a major research area for Theoretical Studies Section. Research is being pursued in understanding and quantifying the entanglment particularly for multipartite quantum systems. Efforts are also made in understanding the decoherence mechanism of qubits coupled with the environment.