CAREER: Investigation of Laser-driven Chemical Reactions by Molecular Dynamics

North Dakota State University Fargo, Fargo ND

Investigators

Abstract

Dmitri Kilin of North Dakota State University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry for theoretical research focused on the control of chemical reactions driven by light, called photoreactions. Light can activate, direct, and speed up chemical reactions otherwise inaccessible by conventional reaction conditions like heat. The goal of this research is to study and simulate the control of photochemical reactions through the tuning of specialized laser light. These researchers develop distributable software with which users can explore light-driven chemical reactions. The software will help advance a wide range of technologies, including energy conversion and storage, and chemical sensing. This work will contribute to theory-guided optimization of thin-film deposition technology, which is important for the miniaturization of electronic circuits towards nano- and sub-nano scales. The educational mission includes the participation of graduate and undergraduate students in professional activities. Outreach activities are focused on providing research experiences that will specifically offer remote, distant learning, and training opportunities. Dr. Kilin will also mentor high school students participating in PICNICS (Parents Involvement with Children, Nurturing Intellectual Curiosity in Science) program hosted at NDSU. The computational description of dynamics under the electromagnetic field remains challenging due to coupled electronic and nuclear degrees of freedom. There are known approaches for independent treatment of subsequent contributing processes: photoexcitation, reorganization and dissipative interaction with electronic degrees of freedom, and molecular and reaction dynamics of nuclear degrees of freedom. However, on a short timescale, all three are coupled. The Kilin group is developing first-principles molecular dynamics approaches for coupled electrons, nuclei, and light to fill the gap in computational investigation of laser-driven chemical reactions. The approaches rely on the combination of Rabi theory and surface hopping approximations. The research program includes an effort for validation of utilized approximations. A hypothesis driven search of acceptable approximations showing accuracy versus numerical cost facilitates an effort of establishing standard approaches for reactions at extreme conditions. Various corrections are being implemented accounting for the quantization of nuclear degrees of freedom, the higher level of electronic structure calculations with increased precision, and the treatment of coherent superposition of quantized states. The practical applications of the improved methodologies focus on photofragmentation of metal-organic compounds, photopolymerization of silicon containing compounds, photografting, and photodesorption of covalent functional groups on carbon nanotubes. The theoretical tools being developed can be applicable to interpret and predict reaction mechanisms and distribution of products for various classes of reactions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.