Computational Mathematics Colloquium | Quantum Molecular Dynamics

Thursday, February 11, 2021 3:30 pm - 3:30 pm EST (GMT -05:00)

Speaker

Pierre-Nicholas Roy | Department of Chemistry, University of Waterloo
http://www.science.uwaterloo.ca/~pnroy/

Title

Quantum Molecular Dynamics

Abstract

Molecular assemblies are often described using classical concepts and simulated using Newtonian dynamics or Classical Monte Carlo methods. At low temperatures, this classical description fails to capture the nature of the dynamics of molecules, and a quantum description is required in order to explain and predict the outcome of experiments. We will present mathematical formalisms and simulation algorithms for the study of nano-confined systems. For instance, the Feynman path integral formulation of quantum statistical mechanics is a very powerful tool that is amenable to large-scale simulations [1]. We will show how path integral simulations can be used to predict the properties of molecular rotors trapped in superfluid helium and hydrogen clusters [2]. We will demonstrate that microscopic Andronikashvili experiments can be viewed as a measurement of superfluidity in a quantum mechanical frame of reference [6]. Issues such as quantization in curved spaces will be addressed. The estimation of entanglement measures in Quantum Monte Carlo simulations will be discussed [3] and applied to confined molecular rotors [7]. Such systems can be realized using molecules confined in endohedral fullerene materials such as H2O@C60 and HF@C60 in peapods assemblies. These systems will be used as a platform to assess the relative merits of many- body wavefunction representations based on path integrals [7], truncated product bases [4], matrix product states [5], and other possibilities such as Restricted Boltzmann Machines [8].

[1] T. Zeng, N. Blinov, K. Bishop, G. Guillon, H. Li, and P.-N. Roy, Comp. Phys. Comm. 204, 170 (2016).
[2] T. Zeng and P.-N. Roy, Rep. Prog. Phys. 77, 046601 (2014).
[3] C. M. Herdman, P.-N. Roy, R. G. Melko, A. Del Maestro, Nature Physics 13, 556 (2017).
[4] T Halverson, D. Iouchtchenko, and P.-N. Roy, J. Chem. Phys. 148, 074112 (2018).
[5] D. Iouchtchenko and P.-N. Roy, J. Chem. Phys. 148, 134115 (2018).
[6] H. Li and X.-L. Zhang and T. Zeng and R. J. Le Roy and P.-N. Roy, Phys. Rev. Lett. 123 093001 (2019)
[7] T. Sahoo and D. Iouchtchenko and C. Herdman and P.-N. Roy, J. Chem. Phys. 152 184113 (2020) [8] I. J. De Vlugt and D. Iouchtchenko and E. Merali and P.-N. Roy and R. G. Melko, Phys. Rev. B 102 035108 (2020)