Fully Automated Incremental Evaluation of MP2 and CCSD(T) Energies: Application to Water Clusters

A fully automated implementation of the incremental scheme for CCSD energies has been extended to treat MP2 and CCSD(T) energies. It is shown in applications on water clusters that the error of the incremental expansion for the total energy is below 1 kcal/mol already at second or third order. It is demonstrated that the approach saves CPU time, RAM, and disk space. Finally it is shown that the calculations can be run in parallel on up to 50 CPUs, without significant loss of computer time.