Date: Monday, November 20, 2023
Time & Venue : 2:00 – 3:00 p.m, CVRH
Name: Prof. Prasenjit Ghosh, Dept. of Physics, IISER Pune
Title: Quantum Delocalization effects on Temperature Dependent Double Proton Transfer in Molecular Crystals of Terephthalic Acid
Double proton transfers (DPTs) are important for several physical processes, both in molecules and in the condensed phase. While these have been widely studied in biological systems, their study in crystalline environments is rare. In this work, using path integral molecular dynamics simulations, we have studied temperature dependent DPT in molecular crystals of terephthalic acid (TPA). In accordance with experimental reports, we find evidence for a double proton transfer induced order-to-disorder transition that is sensitive to the inclusion of nuclear quantum effects. Our simulations show that in addition to the presence of L and R tautomers of terepthalic acid, there are a small but non-negligible concentration of positive and negatively charged pairs of TPA molecules. At the onset of the transition at low temperatures, DPT likely occurs through a tunneling mechanism while at room temperature, likely involving the dominance of activated hopping. Through an analysis of the electronic structure of the system using Wannier functions, we show that the H atom shuttling between the donor and acceptor O atoms involves a proton.
Prof. Prasenjit Ghosh is a Theoretical and Computational Physicist and Materials Scientist at the Department of Physics, IISER Pune. He obtained his PhD in Computational Material Science in 2007 from the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore under the guidance of Prof. Shobhana Narasimhan and Prof. Umesh V. Waghmare. He was a postdoctoral research fellow at the Condensed Matter and Statistical Physics Section of The Abdus Salam International Centre for Theoretical Physics from September 2007 to August 2010 before joining IISER Pune in September 2010.
His group is interested in having a microscopic understanding of the physics and chemistry of materials (from zero dimensional clusters/molecules to three dimensional bulk) and how they interact with their environment, using first principles based computational methods. In particular, the group is interested in materials that have applications in heterogeneous catalysis, photo- and electro-catalysis, thermoelectrics and photovoltaics.