PT Journal AU Warnecke, S Sevryuk, MB Ceperley, DM Toennies, JP Guardiola, R Navarro, J TI The structure of para-hydrogen clusters SO European Physical Journal D JI Eur. Phys. J. D PY 2010 BP 353 EP 358 VL 56 IS 3 DI 10.1140/epjd/e2009-00300-9 LA English AB The path integral Monte Carlo calculated radial distributions of para-hydrogen clusters (p-H-2) N consisting of N = 4-40 molecules interacting via a Lennard-Jones potential at T = 1.5 K show evidence for additional peaks compared to radial distributions calculated by diffusion Monte Carlo (T = 0 K) and path integral Monte Carlo at T <= 0.5 K. The difference in structures is attributed to quantum delocalization at the lowest temperature. The new structures at finite temperatures appear to be consistent with classical structures calculated for an effective Morse potential, which in order to account for the large zero point energy, is substantially softer than the Lennard-Jones potential. ER