Simulating Intramolecular Charge Migration on Attosecond timescales

ended

The ability to control the movement of charge is at the heart of chemistry. With the birth of intense, ultrashort attosecond laser pulses, electronic wave packets can be created in molecules which induce nuclear motion. As a result, the observation and control of electron motion at the atomic level is becoming feasible, leading to the field of attochemistry. In this project, we will develop and use theoretical tools to investigate the potential of these modern light sources to probe and direct this charge migration induced molecular dynamics in chemically important polyatomic molecules. These elementary aspects of laser-matter interactions are governed by quantum mechanics and therefore we will solve the time-dependent Schrödinger equation using state-of-the-art quantum dynamics simulations to address the phenomenon. This will lead to a complete understanding of the underlying mechanism behind the coupled electron-nuclear motion and through a detailed comparison with other available semi-classical studies, a clear indication of their success or failure to theoretically describe such processes will be obtained. Following this, laser control schemes will be designed to enhance desired product yields from these chemical reactions. The key issues that we will address are: (i) Laser induced ultrafast charge migration in benzene and substituents, (ii) Charge migration in the photoinduced ring opening of cyclohexadiene to hexatriene, (iii) Coherent control of coupled electron-nuclear dynamics with attosecond laser pulses. Benzene is the building block of polycyclic aromatic hydrocarbons and the cyclohexadiene to hexatriene reaction plays an important role in the biosynthesis of vitamin D3 from its provitamin dehydrocholesterol. Thereby, each of these objectives has potential societal value and will increase the understanding of the molecular basis of these chemical/biological processes.