Optical and magneto-optical properties of the endohedral complex La@C₈₂ crystal: a Hartree–Fock single-excitation configuration interaction model study

Abstract

The dielectric constant tensor is used to describe the magneto-optical properties of crystals. Using the Hartree–Fock single-excitation configuration interaction model in conjunction with the local field method, the spin-dependent optical dielectric tensor, refractive index, reflectivity, circular dichroism (CD), and birefringence coefficient (θ) of the simple cubic (sc) phase of the La@C₈₂ crystal are calculated when the La atom is off-center. The calculations show that the spin-dependent optical dielectric tensor of the La@C₈₂ crystal is large. The displacement of the La atom from the center of the cage leads to molecular electric dipole moment which influences the magnetic and optical properties of the La@C₈₂ crystal. The Coulomb interactions and effective magnetic moment cause increasing dielectric tensor, CD, and θ. Our results show that the optical excitation in the region where the energy is lower than 2 eV has the strongest optical absorption bands and refractive index in the La@C₈₂ crystal. Also, our results show that CD and θ of the La@C₈₂ crystal are larger than those of the C₆₀ and C₇₀ crystals. We obtained the E_g of 0.27 eV similar to that of the obtained results of the La@C₈₂ thin film with a semiconducting behavior.

Keywords:

• dielectric tensor
• La@C₈₂ crystal
• Hartree–Fock single-excitation configuration interaction model