Sourav Pal


Sourav Pal is an Indian theoretical chemist, a professor of chemistry in IIT Bombay and is the director of the Indian Institute of Science Education and Research Kolkata. Pal is an ex-director of CSIR-National Chemical Laboratory Pune, and adjunct professor at the Indian Institute of Science Education and Research Pune.
He is known for his contribution in quantum chemistry, especially in the field of coupled cluster based methods. His major scientific accomplishments include rigorous development of expectation value as well as extended coupled-cluster functional, development of the response properties to multi-reference coupled cluster theory, the effect of electron correlation and role of exchange effects on the low energy electron molecule scattering, introduction of complex scaling and complex absorbing potential in MRCC theory to calculate electron-atom and electron-molecule resonances accurately. He has developed a non-iterative approximation to coupled-perturbed Kohn-Sham density functional theoretic equations for calculation of non-linear properties, which is implemented in the developers' version of deMon code.
Dr. Sourav Pal has also made significant contributions in the area of reactivity descriptors highlighting the conditions of validity of the principle of maximum hardness, deriving qualitative relation of hardness with polarizability, establishing Hirshfeld population in calculation of condensed Fukui functions and developing local hard-soft-acid-base principle for molecular recognition. Further, among his major scientific contributions is study of anti-aromaticity in metal clusters using ab initio molecular dynamics study of structure, electron localisation function and magnetic ring currents. He has addressed the incorporation of Sn-into Beta Zeolites theoretically using AIMD and is actively engaged in computational study of hydrogen storage properties of materials.

Academic background

Pal obtained his master's degree from the Indian Institute of Technology in 1977, and his doctorate from the Indian Association for the Cultivation of Science, supervised by Debashis Mukherjee. He was subsequently a post-doctoral researcher at the University of Florida with Rodney J. Bartlett in 1986.

Awards and honours

Dr. Sourav Pal is a recipient of various awards and honors.
  1. Chosen as a member of the Editorial Board of International Journal of Molecular Sciences from 2000.
  2. Member Advisory Editorial Board, Current Physical Chemistry, Bentham Science from 2010.
  3. Member, Editorial Board, Journal of Chemical Sciences, published by the Indian Academy of Sciences, Bangalore from 2004.
  4. Member, Editorial Board, Proc. Indian National Science Academy, from 1 January 2006.
  5. Member, Editorial Board, International Journal of Applied Chemistry, from 2005.
  6. Elected as a Life Member of the Society for Scientific Values.
  7. Member, American Physical Society, USA

    Research highlights

His contributions have been made to the diverse areas of theoretical chemical physics and span the intellectually demanding and challenging aspects of methodological and conceptual developments with an eye to applications to chemical problems. Following are the specific areas and details of his work

Frontier theoretical development on molecular electric properties

Highly accurate theories has been developed by taking into account the complex, correlated motion of electrons in molecules for the description of non-linear electric properties. Theories using many-body coupled-cluster methods are based on the evaluation of derivatives of energy with respect to external fields in an analytic manner. Extensive development of these theories were carried by him for molecules, with closed shell configurations. The codes developed by him have a potential use in the description of non-linear molecular materials, with possible applications in electronic devices.
At the next stage, the more demanding cases of open shell systems, which are marked by high degree of quasi-degeneracy were addressed by him
. This creates physical problems, which are theoretically difficult to address. Using a multi-determinant description of reference space, which can address this quasi-degeneracy adequately, coupled-cluster analytic derivative was formulated to compute accurate non-linear properties. This general-purpose analytic derivative formulation is the first one based on multi-reference coupled-cluster method and is a significant development in quantum chemistry. He has implemented the theory to study properties of radicals and excited states.

Theoretical investigation of hard-soft acid-base relation

His early contribution involve an extensive ab initio verification of the principle of maximum hardness. He has studied various properties of hardness and softness in relation to molecular properties, like polarizability. Seminal contributions were made by him in developing new local descriptors for intra- and inter-molecular reactivities. Using local hard-soft-acid-base principle, he has calculated interaction energies with the help of only local descriptors of the interacting systems. He has recently identified "Bond Deformation Kernel" correlating with interaction-induced shifts in O–H frequencies in halide-water clusters. Central to his model is the use of local polarization, which can be described by Normalized-Atom-Condensed Fukui Functions, which is the normal condensed Fukui Function multiplied by number of atoms. Using the NFF and charge transferred to water from halide ion, a BDK has been defined, which appropriately describes the shift in OH frequency.

Study of electron-molecule scattering

Sourav has also made an important study in identifying the exchange effects as dominant contributions to the correlated static exchange potential of the molecule in electron-molecule scattering. The properties of CSE were studied extensively in relation to their use in scattering of electrons by molecules. Recently his group used complex-scaling method within the coupled-cluster method to describe the electron-atom resonance. A complex absorbing potential based and an approximation to this based on multi-reference coupled-cluster method to calculate resonance of molecular anions has also been developed by his group. The procedure is based on the analytical continuation method. The advantage of analytical continuation of the Hamiltonian in the complex plane giving the direct access to the resonances parameters is that they can be represented by using L2 wave function. The essential idea underlying the complex absorbing potentials to calculate the resonances is to introduce an absorbing boundary condition in the exterior region of the molecular scattered target which results in a non-Hermitian Hamiltonian, one of the square-integrable eigenfunctions of which corresponds to the resonant state. The associated complex eigen-value then gives the position and width of the resonance or the auto-ionizing state. The important relaxation and correlation effects are included in the coupled-cluster method.

Density functional response approach for molecular properties

A computationally viable alternative to full analytic response to Kohn-Sham density functional theoretic approach, which solves coupled-perturbed Kohn-Sham procedure in non-iteratively has been formulated by Sourav. In the above procedure, the derivative of KS matrix is obtained using finite field and then the density matrix derivative is obtained by single-step CPKS solution followed by analytic evaluation of properties. He has implemented this in deMON2K software and used for calculation of electric properties.

Development and application of molecular dynamics

He developed ab initio molecular dynamics using Gaussian basis sets and Born-
Oppenheimer approximation to study reactions of finite-sized molecules. His study on structure and electron localisation function of mixed metal clusters has led to the novel evidence of anti-aromaticiticity in metal clusters.
Sn-beta zeolite has attracted recent interest due to better catalytic behaviour compared to Ti-Beta zeolite. Al-free Sn-beta zeolite has been recently synthesized and it has been shown by another group to have efficient catalytic activity in Beyer-Villeger oxidation reactions in presence of H2O2. The structure, bonding and acidity of Sn-beta zeolite has been studied using periodic DFT and it has been demonstrated that incorporation of Sn in BEA framework reduces the cohesive energy and is an endothermic process. Computational study of hydrogen storage materials, like magnesium hydrides using Born Oppenheimer molecular dynamics has been made. In particular, study of hydrogen desorption and the effect of dopants, Al and Si has been made.