Ben Gault (He/Him)

Current Research

Ehrenfest dynamics plus noise: real-time correlated electron-phonon molecular simulation

When current-carrying electrons interact with atomic nuclei, they cause the nuclei to swing more energetically, leading to Joule heating. The study of this phenomenon in nanowires and molecular junctions is partly the focus of the project.

Over the past 30 years, methods like NEGF and CEID have been proposed for this very problem. To be tractable, NEGF has to treat one subsystem as a steady-state bath for the other, but we want to be able to study the coupled dynamics of electrons and phonons under possibly violent departures from the steady-state. Meanwhile, CEID is computationally demanding and can only consider atomic motion at the level of quantum correlation functions, while we seek real-space trajectories.

My research aims to improve Ehrenfest dynamics (ED) by introducing a stochastic noisy force-the main cause of spontaneous phonon emission and Joule heating-and studying the accompanying small corrections to the electron dynamics. This force consists of kicks experienced by the nuclei under current flow. Our proposed corrections to ED include matching driving terms in the quantum Liouville equation for the electronic density matrix.

Biography:

My name is Ben Gault, and I am a PhD student at Queen’s University Belfast, undertaking research on the topic of Joule heating in atomic wires. I graduated from Queen’s in 2024 with First-Class Honours in Mathematics (MMath). During my final year, I undertook a difficult theoretical physics project with my now PhD supervisor, combining pen and paper theory and computation. Our work demonstrated that the absorbed power spectrum of a nanoscale wire, under the nonadiabatic application of a monochromatic laser field, is intimately linked to its excitation spectrum. The project was awarded the William Blair Morton Prize. Outside of my work, I enjoy hobbies such as gaming, as well as taking part in sports such as football, badminton and rugby.

Research Interests:

My research interests are in the area of nanoscale systems, with a particular interest in electron-nuclear dynamics.

Pure Profile:

https://pure.qub.ac.uk/en/persons/ben-gault 

Supervisors:

Dr Tchavdar Todorov and Dr Daniel Dundas