We first studied the dimers composed of a Cn (n = 18, 20, 22, 24, 26, 30, 32, 34, and 36) and a C60 fullerene, C60@Cn. Two minimum structures of C60@C18 were located, as shown in Fig. , in which the C18 faces the hexagonal and pentagonal rings of C60 fullerene, respectively. The former is 0.9 kcal/mol lower in energy than the latter, so in subsequent research, we will only focus on the configuration of the former.