Simone Meloni — Page 2

arXiv2011

Hydrodynamics from dynamical non-equilibrium MD

We review a dynamical approach to non-equilibrium MD (D-NEMD). We show how, using a proper simulation setup, is possible to treat interesting cases in which the initial condition is a stationary non-equilibrium state produced by a suitable dynamical system. We then extend the class of non-equilibrium phenomena that can be studied by atomistic simulations to the case of complex initial conditions consisting in assigning a macroscopic value of a scalar or vector observable or a field. We illustrate the functioning of this method by applying it to the relaxation of an interface between two immiscible liquids. We have shown that our method generate unbiased results while this might not be the case for the often used short time average approach.

physics.comp-ph↗

arXiv2011

Atomistic structure of amorphous silicon nitride from classical molecular dynamics simulations

By means of molecular dynamics simulations based on the Billeter et al. [S. R. Billeter, A. Curioni, D. Fischer, and W. Andreoni, Phys. Rev. B {\bf 73}, 155329] environment-dependent classical force field we studied the structural features of SiN$_x$ samples at various stoichiometries. Our results are in good agreement with experimental data and are able to reproduce some features which so far were not reproduced by simulations. In particular, we identified units containing N--N bonds, which are thought to be responsible for an unassigned peak in the radial distribution function obtained from neutron diffraction data and signals observed in electron spin resonance, X-ray photoemission spectroscopy, electron-energy-loss spectroscopy and optical absorption experiments. We have identified defects which are thought to be the responsible for the high concentration of charge traps that makes this material suitable for building non-volatile memory devices. We analyzed the dependency of the concentration of these defects with the stoichiometry of the sample.

cond-mat.dis-nn↗