Molecular Dynamics

Until very recently, the Green-Kubo (GK) theory of linear response was not deemed compatible with quantum simulation techniques based on density functional theory because the concepts of energy density and current are not well defined at the atomic scale, and because the study of transport coefficients using the GK theory is known to require so long molecular dynamics simulations as to make ab initio techniques unaffordable. Recently, the first of these hurdles was overcome thanks to a paradigm shift based on the concept of gauge invariance of transport coefficients, [1, 2] while the latter was crossed using a novel data analysis technique based on the so-called cepstral analysis of stationary time series. [3]
In this talk we present the first combined application of these theoretical and methodological advances to the quantum simulation of heat transport in amorphous solids using equilibrium ab initio molecular dynamics, with focus on silica glasses.

[1] A. Marcolongo, P. Umari, and S. Baroni, Nat. Phys. 12, 80 (2016).
[2] L. Ercole, A. Marcolongo, and S. Baroni, J. Low Temp. Phys. 185, 79 (2016).
[3] L. Ercole, A. Marcolongo, and S. Baroni, arXiv:1706.01381.