Confinement and correlation effects in the Xe@C60 generalized oscillator strengths

TL;DR

This study investigates how confinement within C60 and electron correlation influence the generalized oscillator strengths of Xe@C60, revealing significant distortions and the importance of multipolar transitions and correlation effects.

Contribution

It provides a comprehensive theoretical analysis of confinement and correlation effects on GOS's in Xe@C60, using combined approximation methods and modeling confinement with different potentials.

Findings

Confinement causes dramatic distortion of GOS's compared to free Xe.

Multipolar transitions significantly contribute to the GOS's.

Electron correlation is crucial for accurate GOS calculations for Xe@C60.

Abstract

The impact of both confinement and electron correlation on generalized oscillator strengths (GOS's) of endohedral atoms, A@C60, is theoretically studied choosing the Xe@C60 4d, 5s, and 5p fast electron impact ionization as the case study. Calculations are performed in the transferred to the atom energy region beyond the 4d threshold, omega = 75--175 eV. The calculation methodology combines the plane wave Born approximation, Hartree-Fock approximation, and random phase approximation with exchange in the presence of the C60 confinement. The confinement is modeled by a spherical delta-function-like potential as well as by a square well potential to evaluate the effect of the finite thickness of the C60 cage on the Xe@C60 GOS's. Dramatic distortion of the 4d, 5p, and 5s GOS's by the confinement is demonstrated, compared to the free atom. Considerable contributions of multipolar transitions beyond dipole transitions in the calculated GOS's is revealed, in some instances. The vitality of accounting for electron correlation in calculation of the Xe@C60 5s and 5p GOS's is shown.