Accuracy of DLPNO–CCSD(T) Method for Noncovalent Bond Dissociation Enthalpies from Coinage Metal Cation Complexes

The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO–CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+, and Au+ complexes. For 33 Cu+–noncovalent ligand dissociation enthalpies, all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass–Kroll–Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to −1.0 kcal/mol. For 24 Ag+–noncovalent ligand dissociation enthalpies, the DLPNO–CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+–noncovalent ligand dissociation enthalpies, the DLPNO–CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the ...