Incremental CCSD(T)(F12*)|MP2: A Black Box Method To Obtain Highly Accurate Reaction Energies

In this work we present a new partitioning scheme for the incremental approach in combination with the efficient (F12*) approximation for explicitly correlated coupled cluster (J. Chem. Phys. 2010, 132, 231102). Furthermore we establish a black-box truncation scheme which provides chemical accuracy for the absolute energies of 81 molecules and 51 reaction energies. The errors in the absolute CCSD(T)/cc-pVTZ-F12 energies due to the local approximations are characterized by mean = -0.24 kJ/mol, σ = 0.49 kJ/mol, mae = 0.37 kJ/mol, rmsd = 0.54 kJ/mol, and range = 3.63 kJ/mol. For the reaction energies we find mean = 0.07 kJ/mol, σ = 0.49 kJ/mol, mae = 0.33 kJ/mol, rmsd = 0.49 kJ/mol, and range = 2.40 kJ/mol. On the basis of these findings it is evident that the incremental scheme provides highly accurate CCSD(T) energies of benchmark quality.