Ground-state properties of a confined simple atom by C₆₀fullerene

Abstract

We numerically study the ground state properties of endohedrally confined hydrogen (H) or helium (He) atom by a molecule of C 60 . Our study is based on Diffusion Monte Carlo method. We calculate the effects of centered and small off-centered H-or He-atom on the ground state properties of the systems and describe the variation of ground state energies due to the C 60 parameters and the confined atomic nuclei positions. Finally, we calculate the electron distributions in x − z plane in a wide range of C 60 parameters.

Double Photoionization of Endohedrally Confined Atoms

“…Moreover, different spherical fullerenes are described varying the well depth. In fact, the energetic structure of these molecules as a function of the magnitude of the cage potential U 0 presents a manifold of avoided crossing between states, even within this two-electron model [17,18]. Similar results were found for endohedrally embedded hydrogen [19].…”

Localization of the valence electron of endohedrally confined hydrogen, lithium and sodium in fullerene cages

“…Most of the studies on X@C N have been done with N = 60 and the endohedral atom located at the center of the fullerene modeled by a spherical potential [26][27][28][29][30][31][32][33][34]. However, as it is shown in Fig.…”

“…Previous research mostly aimed to investigate the shell structure and spectral properties of X@C 60 , in which the enclosed atom is located right at the geometrical center of C 60 , and the fullerene molecule is modeled by a short-range spherical shell with an attractive potential [26][27][28][29][30][31][32][33][34]. Nevertheless, for larger fullerene molecules the equilibrium position of the confined atom is no longer the geometrical center of the molecule [35,36].…”

Endohedrally confined hydrogen atom with a moving nucleus

“…The problem maps to a central field problem for a particle of reduced mass µ, and since µ is very similar to the electron mass, it is usually interpreted as if the nucleus were fixed at the center of the coordinate system. Actually, the center of mass has also a quantum behavior, but it is not generally considered, since the interesting properties such as ionization energies or the excited states structure, only depend on the relative dynamics.The same approach is sometimes applied when the atomic confinement is modeled [9][10][11][12], where the proton is generally considered as an infinitely massive particle fixed in space, acting as a Coulomb center for the electrons clamped somewhere in the box [13,14]. In the case where the proton is not centered, the separation of coordinates is not possible as discussed by Tanner [15] and Amore (and Fernández) [16] for the harmonic oscillator.…”

“…The way to deal with the system while keeping the two-body simplicity is considering the electron-wall interactions of a spherical box or fullerene molecule through boundary conditions [17] or central potentials [18] respectively, as a function of the radial coordinates. The movement of the nucleus can then be considered perturbatively [13], or in the Born-Oppenheimer approximation, where the energy value of the system as a function of its coordinates defines a Potential Energy Surface (PES) through which it moves [19].An alternative way is to consider the system as a threebody problem, consisting of a proton, an electron and a confinement cavity. A first approximation to the ground state solution of the hydrogen atom in an infinitely massive spherical box was introduced by F. M. Fernández [20], who performed a variational calculation with a very simple trial function, which results efficient for strong confinement, i.e.…”