Sculpting the band gap: a computational approach

TL;DR

This paper introduces a computational method that uses Hellmann-Feynman forces related to gap states to design atomic structures with specific electronic properties, demonstrated on amorphous silicon, carbon, and graphene nanoribbons.

Contribution

The work presents a novel approach to incorporate electronic density information into material modeling, enabling targeted band gap engineering in various materials.

Findings

Successfully designed amorphous silicon and carbon models with desired electronic properties.

Validated models with plane-wave density functional calculations.

Demonstrated applicability to 2D materials like graphene nanoribbons.

Abstract

Materials with optimized band gap are needed in many specialized applications. In this work, we demonstrate that Hellmann-Feynman forces associated with the gap states can be used to find atomic coordinates with a desired electronic density of states. Using tight-binding models, we show that this approach can be used to arrive at electronically designed models of amorphous silicon and carbon. We provide a simple recipe to include a priori electronic information in the formation of computer models of materials, and prove that this information may have profound structural consequences. An additional example of a graphene nanoribbon is provided to demonstrate the applicability of this approach to engineer 2-dimensional materials. The models are validated with plane-wave density functional calculations.