Amorphous silicon structures generated using a moment tensor potential and the activation relaxation technique nouveau

TL;DR

This study combines the Activation Relaxation Technique nouveau with a Moment Tensor Potential to generate realistic atom-scale models of amorphous silicon, analyzing their structural, energetic, and mechanical properties.

Contribution

It introduces a novel ARTn-MTP method for creating large, realistic a-Si models that align well with experimental data and lack crystalline grains, advancing modeling techniques.

Findings

Models match experimental data closely

Several models show low coordination defects

No crystalline grains detected in key models

Abstract

Preparing realistic atom-scale models of amorphous silicon (a-Si) is a decades-old condensed matter physics challenge. Herein, we combine the Activation Relaxation Technique nouveau (ARTn) to a Moment Tensor Potential (MTP) to generate seven a-Si models containing between 216 and 4096 atoms. A thorough analysis of their short-range and medium-range structural properties is performed, alongside assessments of excess energy and mechanical properties. The seven ARTn-MTP models are compared with available experimental data and other high quality a-Si models present in the literature. The seven ARTn-MTP a-Si models are in excellent agreement with available experimental data. Notably, several of our models, including the 216-atom, 512-atom, and 1000-atom a-Si models, exhibit low coordination defects without any traces of crystalline grains. Historically overlooked in previous research, our study underlines the need to assess the validity of the continuous random-network hypothesis for the description of perfect amorphous model by characterizing local crystalline environment and to explore the crystallisation process of a-Si through modelling.