Stability of different phases of (C60)2 Structures

Abstract

We investigate the possible binding configurations of pairs of C60 molecules when pushed against each other. Tersoff potential, which represents intramolecular interactions well, has been used to calculate potential energies. We begin relaxation of atomic coordinates at various distances of separation and for all possible mutual orientations of the two molecules. As a result, we have been able to show that several minimum energy configurations exist. Some of these configurations have not been reported earlier. Only two types of dimer structures, involving interlinkage through a single bond, or through so called 2+2 cycloaddition, have been commonly referred in the literature. Our calculation shows that apart from these configurations, many interesting composite phases also result, such as fused and peanut structures and (5,5) and (10,0) nanotubes. A link with experiment to find these structures can be established by application of suitable critical applied pressure in the solid phase, accompanied by high temperature corresponding to orientational melting so that suitable mutual orientations are available. High energy molecular beams of C60 incident upon C60 layers could also achieve the same.