PTC Seminar: November 30, 2021

Date: November 30, 2021 2:00 pm (ET)


  • Lena Simine
    McGill University
  • Pablo Carpio-Martínez
    University of Alberta

Lena Simine

McGill University

Modelling 2D Amorphous Materials: The Curious Case of Monolayer Amorphous Carbon

Abstract: Amorphous materials are common, but they are poorly understood and potentially underutilized. As a class, they are characterized by fast decaying spatial correlations and by rich sets of manifested motifs. The richness of accessible conformations makes simulating them on a computer a difficult task. We address this problem by formulating a new method based on a generative deep neural network that is trained on a set of small-scale samples available either through traditional simulations or through experimental imaging techniques. After training, this model generates new and unseen samples of arbitrary size at linear cost-effectively solving the problem of large-scale simulation of such materials. We apply this method to simulate with an atomistic resolution a recently discovered 2D material, the Monolayer Amorphous Carbon (MAC) – a topologically distinct variant of Graphene.  In this talk, I will describe our new method, its application to MAC, and some of the chemical-physical properties of MAC nano-fragments: steady-state and laser-induced electronic conduction.

Pablo Carpio Martinez

Pablo Carpio-Martínez

University of Alberta

Study of Vibrational Exciton Transfer in a Dimer Chain Under the Influence of a Thermal Gradient

Abstract: In a previous study, we analyzed the effect of introducing lattice displacements into a modified Su-Schrieffer-Heeger (SSH) model chain on the transfer of a vibrational exciton through the different chain-sites. We found that the introduction of lattice displacements by a series of acoustic phonons substantially accelerates the transfer of energy by three orders of magnitude approximately. Even though the transfer was shown to be quite robust in the presence of weak disorder, the effect of coupling the ends of the chain to thermal reservoirs is still an open question. In the present talk, we study the effect of coupling the ends of the chain to thermal reservoirs at different temperatures using adiabatic dynamics. Our findings suggest that for a static chain (i.e., chain with no acoustic phonons) one could enhance the exciton transfer rate by increasing the chain-reservoir coupling strength regardless of the temperature gap. As for the non-static chain (i.e., chain coupled to acoustic phonons), the exciton dynamics is not significantly affected by the presence of thermal gradients. All in all, our findings suggest a platform for building devices that are capable of robust, ultrafast long-range exciton transport.