Quantum simulation of the heat capacity of water

Path integral molecular dynamics simulations have been carried out to evaluate heat capacities of water in gas, liquid, and solid phases. For convergence, a 100-ps simulation run with a large path integral variable (P ∼ 128) was required even by using the double-centroid virial heat capacity estimator. For all states, the quantum corrections to the heat capacities are significantly large. The calculated heat capacities for vapor and ice I _h agreed excellently with experimental data, while that for liquid was less than the experimental value by ∼20% due to the limit of the SPC/F potential model.