Chemistry & Biochemistry Colloquium | Atomistic simulation of disordered materials, Oct. 24

The Chemistry & Biochemistry colloquium series presents Dr. David Drabold discussing "Atomistic simulation of disordered materials" on Oct. 24 from 4:10 to 5:05 p.m. in Walter 145.

Drabold is Distinguished Professor of Physics & Astrono0my at Ohio University.

Abstract: After a historical review of the development of computer simulation and especially molecular dynamics as a tool in condensed matter science, I directly simulate the process of graphitization – the conversion of carbonaceous materials into a graphite-like phase from heating. I show that this often produces a new carbon solid -- layered amorphous graphene[1], and extend the calculation with open boundary conditions to unveil the creation of “Bucky Onions” – multi-shell fullerenes[2]. With a nod to important emerging concepts, I briefly describe a Machine Learning based simulation of an exotic pressure-induced phase transition of amorphous silicon[3] in a 100,000-atom system with density functional accuracy. A remarkable rapid crystallization (into a simple hexagonal phase), occurs near 13 GPa. I show that large, accurate and temporally extended simulations are required to even detect key processes such as the observed crystallization.

[1] R. Thapa, C. Ugwumadu, J. Trembly, K. Nepal and D. A. Drabold, Simulations of Amorphous Graphite, Phys. Rev. Lett. 128 236402 (2022).

[2] C. Ugwumadu, et al., Simulation of multi-shell fullerenes using Machine-Learning Gaussian Approximation Potential, Submitted to Carbon Trends (8/2022)

[3] V. Deringer, N. Bernstein, G. Csanyi, M. Wilson, DAD and S. R. Elliott, Origins of structural and electronic transitions in disordered silicon, Nature 589 51 (2021).