Benchmark study of the interaction energy for an (H_2O)_16 cluster: Quantum Monte Carlo and complete basis set limit MP2 results

摘要

The quantum Monte Carlo method is used to calculate the binding energy of an (H_2O)_16 cluster that has been the subject of several recent theoretical studies. The resulting interaction energy, -165.1(8) kcal/mol, is very close to our MP2 complete basis set limit interaction energy of -164.1 kcal/mol. Comparison of these results with those for the one-, two-, three-, and four-body interaction energies leads us to conclude that the five- and higher-body interactions are attractive, contributing over 2 kcal/mol to the net interaction energy of this (H_2O)_16 isomer.