Unraveling Photochemistry with First-Principles Simulations

From electricity generation with photovoltaics, through efficient synthesis with photocatalysis, to targeted therapeutics with light-activated drugs, photochemistry is at the heart of many of the technological challenges that society needs to overcome in the 21st century. Nonadiabatic molecular dynamics (NAMD) simulations have emerged as a powerful set of tools to provide atomistic details of ultrafast photochemical reactions that are unavailable from experiment alone.

Data-driven Applications of Coarse-grained Molecular Dynamics

Abstract: The simulation of all-atom molecular dynamics is restricted in both length (~nm) and time (ps~ns) scales, limiting its application in modeling microstructure evolution (nm~μm) in hard crystals or conformation dynamics in soft polymers (ns~ms). We turn to modeling coarse-grained molecular dynamics, using approximate, non-Markovian representations of less relevant degrees of freedom. The equations of motion for these effective models can be derived from all-atom simulation data. We will present a few examples and introduce relevant open-source packages.

Formation and dissociation of hydrocarbons under interstellar conditions

Abstract: Hydrocarbons of all shapes and sizes are found throughout the various stages of star- and planet formation. Recently, using radio astronomical observations, a variety of cyclic- and even polycyclic hydrocarbons have been detected in the very cold (10 K) Taurus molecular cloud. These detections challenge our understanding of the chemical formation mechanisms under these low-temperature and low-density conditions.

Theoretical Approaches to Photoinduced Charge Transfer in the Condensed Phase

Abstract: Photoinduced charge and energy transfer in condensed-phase systems plays a crucial role in solar energy conversion, particularly in organic photovoltaic (OPV) materials. This talk will introduce newly developed computational frameworks that integrate three levels of description: rate constants, time-dependent rates, and nonadiabatic dynamics. At the core of these approaches is the linearized semiclassical (LSC) method, which enables the study of electronic transitions in complex many-body systems at an all-atom resolution.

Chemistry and thermodynamics of f-block materials: from nuclear fuels to waste forms

Abstract: New types of fuel materials and ceramics are needed to be studied for the emerging and next generation nuclear reactor technology development. Their development requires our fundamental understanding and accurate description of structures, thermochemical stability, mechanical performance, and phase equilibria. In our group, we use a suite of structural-thermodynamic techniques to achieve this understanding.

Accelerating the Computational Design of Functional Organic Molecules and Polymers

Abstract: Functional materials design often requires that the desired molecules (or materials) simultaneously satisfy multiple desired properties, such as electrochemical properties, stability, and synthetic accessibility. This talk will discuss several strategies we have developed for efficiently navigating chemical space and accelerating the inverse design of new functional organic molecules and materials, and the physical insights we gain during their design and deployment.

On-Demand Control of Single-Molecule Chemistry through Vibrational Characterization and Manipulation

Abstract: Chemical processes hinge on the dynamic rearrangement of nuclei within molecules. Controlling these motions with precision has been a long-standing goal in chemistry. My lab focuses on achieving this by manipulating interactions between individual molecules and their nanoscale environment. We engineer the potential energy surface at this scale to control molecular properties such as structure and reactivity.

Investigating Various Fascinating Aspects of Gold Nanoparticles in DNA Research, Material Science, and Cancer Therapy

Abstract: In this talk, we will explore the intriguing interactions between DNA and gold nanoparticles, focusing on their newly explored binding mechanisms. Key topics will include the selective binding of gold nanoparticles to mismatched and/or single-stranded regions of double-stranded DNA and the subsequent movement of these particles along the DNA molecule over the long molecular distances.

Urban Air Quality in the Anthropocene

Abstract: Urban air quality in the U.S. has generally been improving for many decades. Decreasing emissions of nitrogen oxides (NOx) and anthropogenic volatile organic compounds (VOCs) have caused decreases in ozone concentrations, albeit in a highly non-linear fashion. In this seminar, I will present results from a summer 2022 study in the LA basin. We observed lower VOC emissions than during previous studies. However, concentrations of secondary pollutants had not decreased, indicative of changes in the NOx-VOC regime.

Putting a New Spin on Intermediate Detection and Automated Analysis to Accelerate Electrochemical Discovery

Abstract: Elucidating and controlling the interfacial reactivity of oxygenated intermediates is key to a broad scope of electrochemical studies of catalysts, sensors, and energy storage media. I will present a modern approach to understanding the electrochemical interface using techniques based on small electrodes, new spectroscopic methods, and the use of automated electrochemistry to characterize intermediates such as reactive oxygen species (ROS) and to explore the converstion of oxygenated organics.

UCI Department of Chemistry

Physical Seminar