Electronic Properties of Carbon Nanobelts Predicted by Thermally-Assisted-Occupation DFT.

Sonai Seenithurai,Jeng-Da Chai

doi:10.3390/nano11092224

Abstract

Accurate prediction of properties of large-scale multi-reference (MR) electronic systems remains difficult for traditional computational methods (e.g., the Hartree–Fock theory and Kohn–Sham density functional theory (DFT)). Recently, thermally-assisted-occupation (TAO)-DFT has been demonstrated to offer reliable description of electronic properties of various large-scale MR electronic systems. Consequently, in this work, TAO-DFT is used to unlock the electronic properties associated with C-Belt[n] (i.e., the carbon nanobelts containing n fused 12-membered carbon rings). Our calculations show that for all the system sizes reported (n = 4–24), C-Belt[n] have singlet ground states. In general, the larger the size of C-Belt[n], the more pronounced the MR character of ground-state C-Belt[n], as evident from the symmetrized von Neumann entropy and the occupation numbers of active TAO-orbitals. Furthermore, the active TAO-orbitals are delocalized along the circumference of C-Belt[n], as evident from the visualization of active TAO-orbitals.

Highlights

Nanomaterials 2021, 11, 2224. https://Carbon is one of the richest elements in forming a number of allotropes
Several belt-shaped carbon molecules, which are entirely made of fused 6-membered carbon rings, have been recently synthesized. These carbon nanobelts can be used as templates or seeds to synthesize structurally well-defined carbon nanotubes (CNTs) [15]
In this work, we focus on the carbon nanobelts consisting of n fused 12-membered carbon rings

Summary

Introduction

Carbon is one of the richest elements in forming a number of allotropes. Carbon forms 0D, 1D, and 2D nanostructures, such as the well-known C60 fullerenes (buckyballs), carbon nanotubes (CNTs), and graphene [1,2]. Several belt-shaped carbon molecules, which are entirely made of fused 6-membered carbon rings, have been recently synthesized. These carbon nanobelts can be used as templates or seeds to synthesize structurally well-defined CNTs [15]. The bonding of rings may be linear or sideways, offering numerous possibilities for generating carbon nanobelts with different structures and properties [11,14], and unlocking new applications. Aiming to unlock the ground-state properties of large-scale MR electronic systems, TAO-DFT (thermally-assisted-occupation density functional theory) [31] has been formulated in recent years. TAO-DFT has been combined with AIMD (ab initio molecular dynamics) to further unlock the dynamical properties of large-scale MR electronic systems [36].

Computational Details

Singlet-Triplet Gap

Symmetrized Von Neumann Entropy

Occupation Numbers of Active TAO-Orbitals

Visualization of Active TAO-Orbitals

Conclusions