Structural and elastic properties of amorphous carbon from simulated quenching at low rates

TL;DR

This study uses molecular dynamics simulations to generate and analyze amorphous carbon structures, revealing universal relationships between hybridization, density, and elastic properties despite variations in structure and cohesive energy.

Contribution

It introduces a method to produce amorphous carbon models with varying densities and morphologies using low-rate quenching and analyzes their structural and elastic properties.

Findings

Universal relationship between hybridization, bulk modulus, and density.

Differences in cohesive energy linked to bond-angle distributions.

Structures show potential variations in thermal stability.

Abstract

We generate representative structural models of amorphous carbon (a-C) from constant-volume quenching from the liquid with subsequent relaxation of internal stresses in molecular dynamics simulations using empirical and machine-learning interatomic potentials. By varying volume and quench rate we generate structures with a range of density and amorphous morphologies. We find that all a-C samples show a universal relationship between hybridization, bulk modulus and density despite having distinct cohesive energies. Differences in cohesive energy are traced back to slight changes in the distribution of bond-angles that will likely affect thermal stability of these structures.