Professor Nandini Ananth
Professor Nandini Ananth
Department of Chemistry & Chemical Biology
Host: Professor Aaron Massari
A Study of Singlet Fission in Bipentacenes
We investigate the mechanisms of Singlet Fission (SF), a phenomenon where an initial photo-excited singlet state spontaneously evolves into a correlated triplet state that can subsequently decorrelate into two triplets. We probe different aspects SF in bipentacenes through both high-level electronic structure studies and simple semi-empirical theories to arrive at rules for identifying SF-active chromophores that absorb intensely in the visible region. Further, we study the recombination rates of the correlated triplet state produced by SF using a new, singularity-free formulation for nonradiative rates. We also show that it is possible to identify key vibronic modes in the recombination process. Finally, we discuss the real-time dynamic methods we have developed to enable atomistic simulations of SF.
Professor Ananth's group seeks to understand the molecular origin of chemical selectivity in natural and synthetic systems using theoretical simulation techniques derived from the principles of quantum and classical mechanics. Research interests include:
- Developing semiclassical and path-integral based model dynamics to simulate interesting chemistry in the condensed-phase.
- Developing approximate methods for quantum dynamics that are able to incorporate quantum effects like zero-point energy, tunneling, and coherence and to describe electronically nonadiabatic processes, while retaining the favorable scaling in computational cost with system size exhibited by classical molecular dynamics simulations.
- Understanding the molecular origin of chemical selectivity in natural and synthetic systems.
- Investigating exciton chemistry in organic photovoltaics, multi-electron chemistry in tri-metal-center transition metal complexes, and vibrationally promoted hot-electron chemistry in reactions at metal surfaces.
Goals are to use a combination of theory, electronic structure, and quantum dynamics to 1) uncover the detailed mechanisms of novel charge and energy transfer phenomena, 2) identify productive reaction pathways/intermediates as well as competing loss mechanisms, 3) isolate significant factors, such as chemical environment, relative geometries, and temperature that determine dominant pathways, 4) construct experimentally verifiable hypotheses to enhance charge/energy transport properties of specific materials, and 5) build a database of transferable design principles that can be used predictively in the development of novel materials.
Nandini Ananth was born in Chennai, India. She attended Stella Maris College in Chennai, and graduated with a bachelor's degree in chemistry. She then joined the master's program in chemistry at the Indian Institute of Technology Madras. Here she developed a strong interest in quantum mechanics and carried out research on implementing logic gates for quantum computing using Nuclear Magnetic Resonance. During this time, she also received a Summer Research Fellowship from the Jawaharlal Nehru Center for Advanced Scientific Research and was introduced to semiclassical dynamics at the Indian Institute of Science, Bangalore. This further solidified her interest in theoretical chemistry and chemical dynamics. Ananth moved to the United States to pursue doctoral research at the University of California, Berkeley, working on developing semiclassical methods to model quantum dynamical behavior in complex chemical reactions. Upon graduation, she accepted a position as post-doctoral scholar at the California Institute of Technology, Pasadena, where her research focused on developing path-integral methods for the simulation of electronically nonadiabatic processes in the condensed phase. She joined the faculty of the Department of Chemistry and Chemical Biology at Cornell University in 2012.