Y. Minenkov , E. Chermak , L. Cavallo
J. Chem. Theo. Comp., in press, (2015)
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 experimental measurements. Overall, for the combined data set of 72
coinage metal ion complexes, DLPNO–CCSD(T) results in a MUE below 2.2
kcal/mol and an almost vanishing MSE. As for a comparison with
computationally cheaper density functional theory (DFT) methods, the
routinely used M06 functional results in MUE and MSE equal to 3.6 and
−1.7 kcal/mol. Results converge already at CC-PVTZ quality basis set,
making highly accurate DLPNO–CCSD(T) estimates affordable for routine
calculations (single-point) on large transition metal complexes of
>100 atoms.