Structures, Electronic Properties, Spectroscopies and Hexagonal Monolayer Phase of a Family of Unconventional Fullerenes C64X4 (X = H; F;Cl;Br)

TL;DR

This study uses first-principles calculations to explore the structures, electronic properties, and spectroscopic features of unconventional C64 fullerenes and their derivatives, revealing stability enhancements and potential monolayer formation.

Contribution

It provides the first detailed computational analysis of C64X4 fullerenes, including their stability, electronic structure, and spectroscopic signatures, and predicts their ability to form stable hexagonal monolayers.

Findings

C64 has a spherical ground state with D2 symmetry.

Halogen addition enhances stability and modifies electronic properties.

C64X4 molecules can form stable hexagonal monolayers.

Abstract

A systematic first-principles study within density functional theory on the geometrical structures and electronic properties of unconventional fullerene C64 and its derivatives C64X4 (X = H; F;Cl;Br) has been performed. By searching through all 3465 isomers of C64, the ground state of C64 is found to be spherical shape with D2 symmetry, which differs from the parent cage of the recently synthesized C64H4 that is pear-shaped with C3v symmetry. We found that the addition of the halogen atoms like F;Cl;Br to the pentagon-pentagon fusion vertex of C64 cage could enhance the stability, forming the unconventional fullerenes C64X4. The Mulliken charge populations, LUMO-HOMO gap energies and density of states are calculated, showing that different halogen atoms added to C64 will cause remarkably different charge populations of the C64X4 molecule; the chemical deriving could enlarge the energy gaps and affect the electronic structures distinctly. It is unveiled that C64F4 is even more stable than C64H4, as the C-X bond energy of the former is higher than that of the latter. The computed spectra of C64H4 molecules agree well with the experimental data; the IR, Raman, NMR spectra of C64X4 (X = F;Cl;Br) are also calculated to stimulate further experimental investigations. Finally, it is uncovered by total energy calculations that C64X4 could form a stable hexagonal monolayer.