Accurate Computation of Cohesive Energies for Small to Medium-Sized Gold Clusters

High-level CCSD­(T)-F12-type procedures have been used to assess the performance of a variety of computationally less demanding methods for the calculation of cohesive energies for small to medium-sized gold clusters. For geometry optimization for small gold clusters, the PBE-PBE/cc-pVDZ-PP procedure gives structures that are in close agreement with the benchmark geometries. We have devised a CCSD­(T)-F12b-based composite protocol for the accurate calculation of cohesive energies for medium-sized gold clusters. Using these benchmark (nonspin–orbit vibrationless) cohesive energies, we find that fairly good agreement is achieved by the PBE-PBE-D3/cc-pVTZ-PP method. In conjunction with PBE-PBE/cc-pVDZ-PP zero-point vibrational energies and spin-obit corrections obtained with the PBE-PBE-2c/dhf-TZVP-2c method, we have calculated 0 K cohesive energies for Au2–Au20. Extrapolation of these cohesive energies to bulk yields an estimated value of 383.2 kJ mol–1, which compares reasonably well with the experimental value of 368 kJ mol–1.