Nuclear quantum effects in finite temperature simulations of molecular clusters are determined by taking advantage of a recently developed method based on the Feynman Path Integral. The structural and thermodynamic properties, including the nuclear quantum effects are determined for three Stockmayer clusters. The ionic system contain a lithium ion solvated by six strong dipoles and 12 weaker ones. The presence of the ion in the mixed Stockmayer cluster drastically enhances the fluxional nature of the less polar components which occupy the second solvation layer, whereas the neutral counterpart has the effect of reducing it. The nuclear quantum effects are significant at room temperature and above for the solvated ionic system. These are attributable to two factors: (a) the lightness of the lithium ion and (b) the stiffness of the ion-dipole interactions. At 300 K, the difference between the fully converged quantum and the classical heat capacities is about 1.3 K B for the ionic cluster. This difference is about 10 SDs obtained from 95% confidence estimates of the statistical fluctuations. Cubic convergence is confirmed for temperatures as low as 50 K by regression analysis. The nuclear quantum effects do not change the peak melting temperature of the cluster. K E Y W O R D S nuclear quantum effects, lithium ion, re-weighted random series path integral, generalized coordinates, stereographic projections 1 | INTRODUCTIONClusters are gas phase nano-sized aggregates of matter, they are vitally important for technological advances, and can serve as model systems to untangle and simplify the investigation of otherwise intractable problems at the fundamental level using a combination of theoretical and experimental methods. The contributions along these two lines are so numerous that it would be impossible to provide a meaningful comprehensive review of the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] within the confines of a research article. One fundamental issue that can be addressed theoretically and experimentally using clusters is the determination of the nuclear quantum effects on the dynamics [20] and thermodynamics of microsolvation. Learning about the timescales of solvent rearrangement dynamics as a solute particle suddenly changes its charged state, and how these are impacted by the interaction parameters, the nuclear quantum effects, and the size of the cluster, are the long term objectives of our efforts. In this work we focus on the equilibrium properties since these will provide the needed insight as well as the starting points for later quantum dynamic studies.The determination of nuclear quantum effects in finite temperature simulations of molecular clusters, such as those concerning us here, remains challenging. In these complex systems, the intramolecular degrees of freedom are associated with frequencies that are many times larger than