Effects of exchange-correlation potentials on the density-functional description of C60 versus C240 photoionization

Abstract

We study the photoionization properties of the C60 versus C240 molecule in a spherical jellium frame of density functional method. Two different approximations to the exchange-correlation (xc) functional are used: (i) The Gunnerson-Lundqvist parametrization [Phys. Rev. B 13, 4274 (1976)] with an explicit correction for the electron self-interaction (SIC) and (ii) a gradient-dependent augmentation of (i) by using the van Leeuwen and Baerends model potential [Phys. Rev. A 49, 2421(1994], in lieu of SIC, to implicitly restore electrons' asymptotic properties. Ground state results from the two schemes for both molecules show differences in the shapes of mean-field potentials and bound-level properties. The choice of a xc scheme also significantly alters the dipole singlephotoionization cross sections obtained by an ab initio method that incorporates linear-response dynamical correlations. Differences in the structures and ionization responses between C60 and C240 uncover the effect of molecular size on the underlying physics. Analysis indicates that the collective plasmon resonances with the gradient-based xc-option produce results noticeably closer to the experimental data available for C60.

Photoionization and photofragmentation of singly charged positive and negative Sc3N@C80 endohedral fullerene ions

“…Most of the work on photoprocesses involving fullerenes and endohedral fullerenes is theoretical ( [8,17] and references therein) because experiments are hampered by the limited availability of pure fullerene samples. The problem of sample purity can be overcome by employing mass-selective preparation of fullerene targets.…”

Electron vacancy-level dependent hybrid photoionization of the F−@ C60+ molecule: a novel effect

“…We model the bound and continuum states, and the ground state potential, using the independent particle DFT approximation that utilizes the Leeuwen-Baerends (LB) exchange-correlation functional [28]. This functional involves the gradient of the electron density in the scheme described earlier [29]. We chose the spherical frame with F or F − situating at the center of C 60 .…”

A density functional theory based comparative study of hybrid photoemissions from Cl@C60, Br@C60 and I@C60

“…We model the bound and continuum states, and the ground state potential, using the independent particle DFT approximation that utilizes the Leeuwen-Baerends (LB) exchange-correlation functional [27]. This functional involves the gradient of the electron density in the scheme described earlier [28]. A core of 60 C 4+ ions for C 60 is constructed by smearing the total positive charge over a spherical shell with known molecular radius R = 6.70 a.u.…”

“…The Kohn-Sham equations for the system of 240 C 60 electrons (four valence 2s 2 2p 2 ) and free atomic (anionic) results. For empty fullerenes the model describe two single electron bands in the ground state with one of σ (no radial node) and another of π (one radial node) character [28].…”