We investigate the electronic structure of AuCl3 graphite intercalation compounds by means of discrete variational (DV)-Xα molecular orbital calculation and ultraviolet photoelectron spectra (UPS). DV-Xα calculation of the Au2Cl6 intercalate reveals the importance of relativistic effect due to the presence of heavy Au atoms. The terminal Cl 3p orbital contributes mainly to the lowest unoccupied molecular orbital (LUMO) of Au2Cl6 molecule in addition to the minor contribution of the Au 5d component. The calculation of (Au2Cl6)-0.5, which is considered to be intercalate species realized in graphitic galleries through charge transfer from graphite, suggests that the Au2Cl6 intercalate band is located at around the Fermi level EF as well as the graphitic π-band. As a consequence, the density of states at EF is 2-3 times larger than that expected only by the graphitic π-band, which is consistent with optical reflectance, magnetic susceptibility, and the electronic specific heat. The small hump around EF in the UPS of AuCl3-GIC is considered to be associated with the intercalate band. The overlap population analysis suggests the bonds between gold and chlorine atoms in Au2Cl6 become weaker when the 0.5 electron transfer from graphitic π-band to Au2Cl6 molecule. Therefore, the interatomic distances in the Au2Cl6 molecule are found to become elongated, consistent with the experimental results of the Raman spectra.
- Discrete variational (DV)-Xα molecular orbital calculation
- Graphite intercalation compounds (GICs)
- Ultraviolet photoelectron spectroscopy (UPS)
ASJC Scopus subject areas
- Physics and Astronomy(all)