CLASSICAL MONTE-CARLO SIMULATIONS OF RELAXED TRAPPING SITE STRUCTURES IN LI ATOM DOPED SOLID NE

Results of classical Monte Carlo simulations of Li atom doped fcc Ne solids are presented. Li atom trapping sites based on four-atom and six-atom vacancies required only minor relaxation of the matrix surroundings to reach equilibrium. Trapping sites based on one-atom and two-atom vacancies were unstable and rearranged to yield crowded versions of the relaxed four-atom trapping site. The lattice strain associated with the crowded trapping sites could be relieved by the incorporation of nearby additional vacancies. These results are all consistent with the intuitive concept of a minimum volume trapping site in a van der Waals guest/host system; for the Li/Ne system apparently at least four Ne atoms must be removed to accommodate a Li atom. In all cases, the energies of the trapped Li atoms were at least almost-equal-to 0.25 eV above the energy of a Li atom separated from close-packed solid Ne, indicating that Li atoms are indeed unwelcome in solid Ne.