Projects

Relativistic electronic structure calculation can use the coupled-cluster method with 2-or 4-component spinors as 1-particle basis functions, but the 4-component Dirac Coulomb Hamiltonian based correlation methods can be prohibitively expensive. In our group, we are trying to reduce computational cost using frozen natural spinors.

Radiation damage to the genetic material is one of the profound threats to living organisms on this planet.  High energy radiations can structurally alter DNA by causing base damage, base release and strand breaking.  In our group, we try to understand the low energy induced pathways of radiation damage.

Wavefunction based methods are most accurate and can be improved systematically. However, high computational cost restricted their use beyond small molecules. We are using an alternate approach to identify the relation between the exact and the approximate wavefunctions using a machine learning algorithm. This approach will ensure the use of a physically meaningful model and avoid the brute force use of computational power to extract trends from the available data.

Most of the biological phenomenon happen in the presence of the environment. Treating the environmental effects in excited states are quite complicated due to the rapid change in the character of the wave-function upon excitation. We are developing novel QM/MM methods for treatment of environmental effects (including but not limited to solvations) for excited, ionized and electron attached states. For all practical purposes, calculation of environment effects is very important.

The local correlation technique is one of the most active fields of quantum chemical research.  However, local correlation methods do not work well for excited states as they are non-local by nature. We use a unique combination of natural orbitals, similarity transformation techniques, and sem-numerical approximations to reduce the computational scaling of wave-function based excited states methods.

Addition of extra electrons to molecules and clusters leads to fascinating properties. It is our aim to understand the nature of the forces that help (or deter) the electron attachment process to get an insight into the heart of the anions.