Geometric and electronic properties on stage-1 FeCl3-graphite intercalation compounds

TL;DR

This study uses first-principles calculations to analyze the geometric and electronic properties of stage-1 FeCl3-graphite intercalation compounds, revealing detailed hybridizations, charge transfer, and doping effects.

Contribution

It provides a comprehensive first-principles analysis of the geometric structures, electronic hybridizations, and charge transfer mechanisms in FeCl3-graphite intercalation compounds, highlighting the role of van Hove singularities.

Findings

Identification of multi-orbital hybridizations in FeCl3-graphite

Charge transfer results indicating p-type doping of graphene layers

Detailed analysis of van Hove singularities related to intercalation effects

Abstract

The calculated results of FeCl3 graphite intercalation compounds show the detailed features. The stage-1 FeCl3-graphite intercalation compounds present diversified electronic properties due to the intercalant. The first-principles calculations on VASP are utilized to analyze the essential properties, such as the geometric structures, spatial charge distributions, charge variations, band structures and density of states. The density of states displays full information for an explanation of the hybridizations with the special structures van Hove singularities on it. The van Hove singularities in graphite-related systems are very important and can provide full information for examining the intercalation effects. The orbital-decomposed density of states for C atoms shows that the {\pi} bondings are orthogonal to the sp2 bondings and the C-C bondings retain in the intralayer C atoms. The Fe atoms and Cl atoms form the Fe-Cl bondings at some unique energy range, presenting the multi-orbital hybridizations of [4s, 3dxy, 3dyz, 3dxz, 3dx2-y2, 3dz2]-[3px, 3py, 3pz]. For C-Cl and Cl-Cl bonds, the unique van Hove singularities exhibit their coupling interactions, revealing the multi-orbital hybridizations of [3px, 3py, 3pz]-[ 3px, 3py, 3pz] and [3s, 3px, 3py, 3pz]-[3s, 3px, 3py, 3pz], respectively. The Fe-Cl bondings arise from multi-orbital hybridizations of [4s, 3dxy, 3dyz, 3dxz, 3dx2-y2, 3dz2]-[ 3px, 3py, 3pz]. Due to the band structures and density of states, the multi-orbital interactions between intercalants and graphene layers dominate in the low-lying energy range. The charge transfers per atom (electrons/atom) for C, Fe, Cl are -0.02 e/atom, -0.28 e/atom and +0.46 e/atom, respectively. Thus, the C atoms in graphene layers present as positive ones after intercalation, i.e., the graphite system exhibit p-type doping features in agreement with previous study.