Optical and magneto-optical properties of the simple cubic phase of the C₆₀crystal

Abstract

Using the Hartree-Fock and single configuration interaction model in conjunction with the local field method, the dielectric tensor, refractive index, circular dichroism, birefringence coefficient and the effects of spatial dispersion on the spectrum of the transverse normal polariton waves of the simple cubic phase of the C 60 crystal are calculated. Our results on magneto-optical circular dichroism in the energy range 3-4 eV almost reproduces the reported experimental results. Also, our results on the effect of spatial dispersion, compared with the non-dispersive case, indicate that the first branch of the transverse normal polariton in the C 60 crystal is due to the coupling of the second excitonic state of the C 60 molecule with the electromagnetic field and the first excitonic state has very weak coupling.

Nonlinear optical properties of the M @ C60 endohedrals (M = Cs, Li, and Na)

“…These results conform to our results in Table II. Our results in Tables I–III indicate that the static (hyper) polarizability of C 60 24–26 is smaller than the static (hyper) polarizability of M at C 60 . The main reason for this is that, in Table IV, the values of the excitation energies calculated for M at C 60 are smaller than excitation energies calculated for C 60 .…”

“…The second term is the long-rang Coulomb interaction in the form of Ohno potential that presents the electron-electron interaction between p electrons [25,26].…”

“…The second term is the long‐rang Coulomb interaction in the form of Ohno potential that presents the electron‐electron interaction between π electrons25, 26. where n el is the number of electrons per site, r ij is the distance between the i th and j th sites, and is the Ohno potential27.…”

“…The matrix elements of H HP and H ′ (the excitation Hamiltonian) with respect to the electron‐hole states are equal to and where E μ is the HF state energy and δ s = 1 is used for the spin singlet and δ s = 0 is used for the triplet states. The J and K terms in equation have the following forms25, 26: where V i,j = U and V i,j = W ( r i,j ) for i ≠ j and U = 2 V = 4 t . Diagonalization of the total Hamiltonian H , gives the singlet and triplet excitonic states of M @ C N molecule.…”

Optical and magneto-optical properties of the monoclinic phase of the C70crystal

“…The Ohno potential, [(1/u) 2 + (r i, j /r 0 V ) 2 ] −1/2 , is adopted as the form of the Coulomb repulsion between two π orbitals with distance r i, j [13]. Here U is the interaction strength at r i, j = 0 and V is the strength of the long-range part; the Coulomb interaction is treated by HF approximation and the single-excitation CI method for the Coulomb potential [12,22]. The adiabatic approximation is forced on the bond variables, which are determined self-consistently using the Su-Schrieffer-Heeger (SSH) method [14].…”