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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:59 |
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Conference: Bucharest University Faculty of Physics 2022 Meeting
Section: Atomic and Molecular Physics. Astrophysics. Applications
Title:
Formation mechanism of endohedral He@C20H20
Authors:
Leonard Constantin GEBAC; Mircea BERCU; Valeriu FILIP
*
Affiliation:
University of Bucharest, Faculty of Physics, Department of Structure of Matter, Earth and Atmosphere Physics, Astrophysics, 405 Atomistilor Street, Magurele, Ilfov
E-mail
leonard.gebac@unibuc.ro
Keywords:
molecular dynamics, dodecahedrane, encapsulation, atom oscillator
Abstract:
The highest symmetry collision between He and dodecahedrane C20H20 is analyzed in the framework of ab initio Unrestricted Hartree-Fock, 6-31G basis set, molecular dynamics simulations at different initial kinetic energies of the incident helium atom, ranging in between 14 and 28 eV. The interaction between He and the cage-like molecule is described by the static and the dynamic potential energies. It is observed that the dynamic potential barrier height is variable and is a function of the initial kinetic energy of the He atom. At the threshold of the reactive collision, that is, perpendicular through the center of a carbon pentagon ring, the barrier for the encapsulation is found to be very close to that reported by experiments and also by higher level approximation methods. Geometric and energetic parameters are being monitored at each time-step of 0.1 fs of the simulations in order to describe the encapsulation process in great detail. The dependence of the geometric parameters (radius of the cyclopentane ring, distance between first and second order neighbors and CH bond length) versus the position relative to the collision site, reveal a flower-like opening of the cage, followed by a swallowing of the incident atom. Furthermore, the distribution of He kinetic energy on to cage translation, vibration and deformation is being observed as a function of the initial kinetic energy of He and also of position. At threshold, and also at higher incident energies of helium, the dependence of the kinetic energy of He shows the absorption of the projectile inside the cage. The stability of this quantum oscillator revealed by almost stable frequencies in the THz range, makes it suitable for advanced applications.
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