STABILITY OF BINARY CLUSTERS OF FULLERENE MOLECULES

Using Girifalco's potential for describing the interaction between ful lerene molecules, we performed molecular dynamics simulations to obtai n the ground-state structures of (C-70)(n-x)(C-60)(x) clusters (11 les s than or equal to n less than or equal to 22; 0 less than or equal to x less than or equal to n - 1). For all values of x, (C-70)(13-x)(C-6 0)(x) clusters have a closed-shell icosahedral structure that is more stable than those of neighboring (C-70)(n-x)(C-60)(x) clusters; and fo r 2 less than or equal to x less than or equal to 10, (C-70)(19-x)(C-6 0)(x) clusters have a double icosahedral structure that exhibits simil arly enhanced relative stability for 2 less than or equal to x less th an or equal to 9. The discrepancy between this latter result and exper imental findings for ionized fullerene clusters, which suggest that [( C-70)(19-x)(C-60)(x)](+) is more stable than the homologous 18- and 20 -member clusters for all x, is tentatively attributed to the ionizatio n-induced alteration of the intermolecular potential. (C) 1998 America n Institute of Physics. [S0021-9606(98)02722-6].