Computational chemistry is one of many exciting research focuses at NYU Shanghai. Taking full advantage of NYU Shanghai’s interdisciplinary environment and making creative use of diverse research tools, young scientists at NYU Shanghai extended their research work to the frontiers of global academia to create a new model of graduate student training, The NYU Shanghai-ECNU Joint Graduate Training Program (N.E.T.).
Established jointly by NYU Shanghai and ECNU, N.E.T enables its students to benefit from the rich research, network, and educational resources available from both institutions. Students communicate directly with and work alongside distinguished scholars from all over the world, access cutting-edge research tools, and expand their academic horizons to advance the future of their scientific research. Interested in exploring the latest research topics in computational chemistry? Let’s take a closer look at Professor Sun’s laboratory.
Professor Xiang Sun
Xiang Sun is an Assistant Professor of Chemistry at NYU Shanghai, Global Network Assistant Professor at NYU, and a core member of the NYU-ECNU Center for Computational Chemistry at NYU Shanghai. Prior to joining NYU Shanghai, he was a postdoctoral research fellow at the University of Michigan, Ann Arbor and a visiting scholar at the University of California, San Diego. He holds a Ph.D. in Chemistry from Brown University and a B.S. in Chemical Physics from the University of Science and Technology of China (USTC). His research focuses on studying quantum dynamics in condensed-phase systems. After joining NYU Shanghai, Professor Sun has carried out extensive cooperation with domestic and foreign universities and research institutes, and started the Lab of Quantum Dynamics in Condensed-Phase Systems at NYU Shanghai.
From left to right: Ningyi Lyu, Zengkui Liu, Zhubin Hu, Xiaofang Zhang, Dominikus Brian, Xiang Sun
The Lab of Quantum Dynamics in Condensed-Phase Systems
The lab’s research focus is to study quantum dynamics in condensed-phase systems, such as liquid solutions, surfaces, biological macromolecules, and energy-conversion nanomaterials. A fundamental goal of the lab’s research is to obtain a molecular-level understanding of how electronic and vibrational excitation influence the mechanisms, outcomes, and spectroscopic signatures of dynamics in these complex molecular systems. Since electronic and vibrational relaxation usually have a quantum nature, it is highly desirable to have methods that accurately describe the relevant quantum dynamical effects, while still being computationally feasible for large-scale systems in the same way that classical methods do. The laboratory is focused on developing semiclassical and mixed quantum-classical methods from classical molecular dynamics (MD) techniques for understanding dynamics following molecular excitation with the help of statistical mechanics, quantum chemistry, and Feynman’s path integral formalism. Having an insight into many-body dynamics helps us learn the molecular lessons of ultrafast spectroscopies and gain a deeper understanding of charge and energy transfer dynamics in light-harvesting biomolecules and organic photovoltaic materials. The laboratory has produced a number of research results that have appeared in journals such as Nature Communications, Journal of Chemical Theory and Computation, and The Journal of Chemical Physics.
Research Highlights
Recently, the Lab of Quantum Dynamics in Condensed-phase Systems and its collaborating team have systematically developed the charge transfer rate theory based on the linearized semiclassical nonequilibrium Fermi’s golden rule. It combines electronic structure calculations and molecular dynamics (MD) simulations to investigate organic photovoltaic materials related to solar cells. The lab also developed CTRAMER, an open-source software package for calculating interfacial charge-transfer rate constants in condensed matter. Compared with traditional methods, this method is unique in that it can explicitly display how the movement of solvent molecules can influence electron transfer rate. Since the computing load is similar to that of molecular dynamics, it can perform all-atom level simulations in a condensed state.
The laboratory has also developed the nonequilibrium Fermi’s golden rule (NE-FGR) all-atom theory for the ultrafast processes of light-induced charge transfer, and proposed a way to calculate time-dependent rate coefficients called the Instantaneous Marcus theory (IMT) and its linear-response and nonlinear-response formulations. In the simulation of the Carotenoid–Porphyrin–C60 molecular triad in explicit tetrahydrofuran, researchers discovered that the transient rate is 40 times faster when nonequilibrium effects are accounted for. This provides a computational means for understanding the molecular mechanism of solar energy conversion. In addition to this project, the laboratory also developed a path-integral molecular dynamics (PIMD) method for the nuclear quantum effect in the ultrafast spectra of liquids and applied it to the calculations of two-dimensional Raman spectroscopy, which will lead to the simulation of nuclear quantum effects in two-dimensional ultrafast spectroscopy.
At present, the laboratory is actively developing a variety of quantum and semiclassical dynamics methods. Combining machine learning and other methods, it hopes to describe the dynamic properties of light-harvesting molecules in condensed phases more accurately and provide theoretical support for designing better renewable energy conversion materials.
The Uniqueness of the Lab and the Scientific Research Experience of Students
From a graduate student’s perspective, can you talk about the uniqueness of Professor Sun’s lab?
Zengkui Liu: The lab embodies a perfect combination of theory and practice.
Dominikus Brian: In Professor Sun’s lab, we can experience and practice both the "theoretical" and the "computational" parts of computational chemistry. We learn programming, develop software, and are further developing computational chemistry theories. I In most research groups, it is rare to have the perfect environment and conditions for research development and, as such, I feel particularly honored; I cherish being one of the members of Professor Sun's laboratory.
Xiaofang Zhang: When I face any technical problems during my scientific research, Professor Sun is always able to patiently guide me through the process in accordance with my aptitude, and I always learn a lot.
Zhubin Hu: In Professor Sun’s laboratory, you can really feel how rigorous theoretical derivations can help you to gain a better understanding of theoretical methods and how to apply them. The lab has a scientific administrative model for managing its research programs and projects, and the research works are carried out in an orderly manner. In the lab, we not only use theoretical derivations, calculations and programming, but also apply theoretical methods to solve practical problems. I have benefited a lot from being part of the research team.
After starting your research career in Professor Sun’s lab, what is your most impressive research experience?
Dominikus Brian: In Professor Sun’s Lab of Quantum Dynamics in Condensed-phase Systems, we are free to explore research topics and are exposed to a wide range of research directions. Under such conditions, we have ample opportunity to acquire a lot of interdisciplinary knowledge.
Zengkui Liu: A theoretical understanding is merely theoretical when you first begin to understand it in a textbook. You will, however, be able to gain a new understanding of a theory after deriving it yourself. And you will especially gain a better grasp of it when you write your own program and get it to run successfully. What’s crucial is to have the experience of programming and testing the theory all on your own.
Xiaofang Zhang: The laboratory gives us a good scientific research environment. I sometimes set aside a day to derive formulas. I think this is necessary for me to understand the entire system and process. Sometimes just taking a break from programming might help me to debug successfully!
Zhubin Hu: In the rigorous academic atmosphere of the laboratory, I realized that codes must be strictly tested and debugged before and after completion. Don't blindly believe the results or data given in the literature (they are sometimes inconsistent). If you have any doubts about it, try reproducing the results yourself. When you try to reproduce the results in the literature, make sure the parameters, conditions, expressions, and so on in the literature correspond exactly to the ones that you use.