Two- versus three-dimensional melting and spontaneous reversing isomerization in isolated SF 6-(Ar) 9 van der Waals clusters

Abstract

Molecular dynamics simulations for SF 6-(Ar) 9 clusters at effective temperatures in the range 5–45 K show that the system undergoes two different “melting” transitions, one at T≈15 K marking the onset of Ar atom mobility within a unimolecular layer around the SF 6, and a second at T≈35 K marking the onset of facile Ar atom motion out of and back into this layer. Moreover, on a narrow interval midway between these two points, the nine Ar atoms show a propensity for spontaneously isomerizing into and out of a long-lived near-rigid two-layer structure.