Direct Path-Integral Monte-Carlo simulations of H+5/D+5 clusters: thermal equilibrium state properties

Classical and path integral Monte Carlo studies for the H+5 cluster and its deuterated counterpart are reported, based on an analytical CCSD(T) potential surface, and a novel realistic DFT 'on the fly' based potential schemes. Thermal equilibrium energies and probability density distributions are obtained for H+5 and D+5, and their molecular structure shows strong spatial delocalization with highly anharmonic character. The implementation of such combined PIMC/DFT approach to study nuclear quantum fluctuation on the electronic properties of larger protonated hydrogen clusters is also discussed.