Electron correlation in 2D periodic systems

TL;DR

This paper demonstrates that bootstrap embedding (BE) accurately predicts electron correlation energies and structural properties in 2D materials, including complex twisted bilayer graphene, with high efficiency and precision.

Contribution

The study introduces the application of bootstrap embedding to 2D materials, showing it can efficiently and accurately handle electron correlation without explicit reciprocal space dependence.

Findings

BE recovers ~99.5% of correlation energy in 2D systems

BE predicts lattice constants and bulk moduli with high accuracy

Correlation energy in twisted bilayer graphene varies with twist angle

Abstract

Given the growing significance of 2D materials in various optoelectronic applications, it is imperative to have simulation tools that can accurately and efficiently describe electron correlation effects in these systems. Here, we show that the recently developed bootstrap embedding (BE) accurately predicts electron correlation energies and structural properties for 2D systems. Without explicit dependence on the reciprocal space sum ($k$-points) in the correlation calculation, BE can typically recover $\sim$99.5% of the total electron correlation energy in 2D semi-metal, insulator and semiconductors. We demonstrate that BE can predict lattice constants and bulk moduli for 2D systems with high precision. Furthermore, we highlight the capability of BE to treat electron correlation in twisted bilayer graphene superlattices with large unit cells containing hundreds of carbon atoms. We find that as the twist angle decreases towards the magic angle, the correlation energy initially decreases in magnitude, followed by a subsequent increase. We conclude that BE is a promising electronic structure method for future applications to 2D materials.