n-body decomposition approach to the calculation of interaction energies of water clusters

A new methodology is proposed in which large basis set MP2-level calculations can be extended to water clusters with as many as 50 monomers. The computationally prohibitive scaling of traditional MP2 calculations is avoided by the use of an n-body decomposition (NBD) description of the cluster binding energy. The computational efficiency of the NBD approach is demonstrated by the application of the method in a Monte Carlo simulation Of (H2O)(6). Future development will further permit accurate MP2 calculations on clusters as large as (H2O)(50).