Research

I have been participating in a number of research projects. The following is a summary of what I am currently pursuing for research projects. Links to some of my previous work can be seen on my Writings page.

These research projects are listed from most to least recent. Within each project heading, the objectives and techniques are presented chronologically to better explain the research process.

Photophysics of Organometallic Complexes Featuring Two Metal Centers

Applications and Models of Quantum Dynamics

My previous research work (some of it published!) with the Xiaosong Li Research Group was primarily focused on looking at time-dependent quantum mechanical phenomena in chemical systems. The vast majority of my work looked at the interactions between light and molecules, probing processes in excited state transitions and what are commonly termed nonadiabatic dynamics.

Often these dynamics may be more simply represented in what is called the diabatic representation . Flip-flopping between techniques is often a powerful way to simplify the formulations and visualizations of some rather complex couplings and processes in quantum dynamics and quantum chemistry in general.

Being naturally lazy, er… I mean efficient, I have used these diabatization techniques extensively and to great effect in my research over the last three years to study some rather complicated and tantalizing processes and phenomena in photochemistry.

One such complicated system is a dimer complex consisting of two platinum metal atoms connected by a “frame” consisting of carbon, nitrogen, and hydrogen atoms. This complex has the curious property that, when excited to a low-lying excited state , the electron density around the metal centers migrates (transfers) up to a pair of phenylpyridine ligands.

In the excited states, a number of competing factors increase the complexity of studying the movement of electrons and how they interact with moving nuclei. One such source of complexity in these systems is inherent in the nature and energetic arrangement of low-lying charge transfer states. At first the system is excited into a superposition of spin-paired singlet many-body states by a laser pulse. Then, the excited state superposition rapidly dephases into a single excited state, S$_1$, which proceeds to transfer electron populations to another — unusually long-lived — superposition of lower-energy triplet (spin-unpaired) excited states. This has all been observed in experiment, however a total understanding of the charge transfer pathway, its associated kinetics, and the structures supporting the maintenance of triplet coherences remains elusive.

My theoretical and computational work investigating a few hypothetical charge transfer pathways is discussed in the following sections. I did not undertake this work alone, so I have several collaborators with whom I have interacted and co-written throughout the course of this study (please see my Writings page for more information).

It should also be stressed here that there have been limitations placed on computing resources, software infrastructure, and time. As a result, many of the models and simulation techniques applied below are carefully constructed and selected such that they maximize our understanding of these processes while remaining computationally and mathematically tractable given the resource constraints.