【正】 The eigenvalues of a Ar<sub>3</sub> cluster subject to a Lennerd-Jones pairwise interaction arecalculated by using harmonic oscillator product states,The geometric structures and theinternal motion of a Ar<sub>3</sub> cluster are investigated from an anaysis of the wavefunctions.Thisinvestigation reveals the general shape and motional features of a Ar<sub>3</sub> cluster.