Isotope effect on the melting of para-hydrogen and ortho-deuterium clusters

Path integral Monte Carlo calculations have been used to investigate the isotope effect on the “melting” of small clusters of para-hydrogen (p-H2) and ortho-deuterium (o-D2). While clusters of (o-D2)N with N=13 and 55 exhibit a quantum-lipid→quantum-solid “freezing” transition in a temperature regime where the effects of Bose statistics are unimportant, the corresponding (p-H2)N clusters do not.