Prediction of Bond Dissociation Energies/Heats of Formation for Diatomic Transition Metal Compounds: CCSD(T) Works

Abstract

It was recently reported ( J. Chem. Theory Comput. 2015 , 11 , 2036 - 2052 ) that the coupled cluster singles and doubles with perturbative triples method, CCSD(T), should not be used as a benchmark tool for the prediction of dissociation energies (heats of formation) for the first row transition metal diatomics based on a comparison with the experimental thermodynamic values for a set of 20 diatomics. In the present work the bond dissociation energies as well as the heats of formation for those diatomics have been calculated by the Feller-Peterson-Dixon approach at the CCSD(T)/complete basis set (CBS) level of theory including scalar relativistic corrections and correlation of the outer shell of core electrons in addition to the valence electrons. Revised experimental values for the hydrides are presented that are based on new heterolytic R-H bond dissociation energies, which are needed for analysis of the mass spectrometry experiments. The agreement between the calculated bond dissociation energies and the revised experimental values of the hydrides is good. Good agreement of the calculated bond dissociation energies/heats of formation is also found for most of the chlorides, oxides, and sulfides given the experimental error bars from experiment and those of the transition metal atoms in the gas phase. Thus, reliable results can be achieved by the CCSD(T) method at the CBS limit. The use of PW91 orbitals for the CCSD(T) calculations improves the predictions for some compounds with large T diagnostics at the HF-CCSD(T) level. The optimized bond distances and calculated vibrational frequencies for the diatomics also agree well with the available experimental values.

On Achieving High Accuracy in Quantum Chemical Calculations of 3d Transition Metal-Containing Systems: A Comparison of Auxiliary-Field Quantum Monte Carlo with Coupled Cluster, Density Functional Theory, and Experiment for Diatomic Molecules

“…For CrO we also show the experiment selected by Dixon and co-workers in Ref. 23, since it is not consistent with that chosen by de Oliveira-Filho and co-workers, 7 given the reported uncertainties. Figure 7: Same as Fig.…”

“…23 Their selection of best experimental values for the 3dMLBE20 set are listed in Table 5 of Ref. 23 Recently, Morse has reviewed his group's progress in obtaining highly precise measurements using resonant two-photon ionization spectroscopy to obtain predissociation thresholds that are equivalent to the BDE's of those diatomics with a very high density of states. 49 This experiment works by increasing the frequency of the incoming laser pulse until the excited state cation can no longer be detected (the predissociation threshold), because it has dissociated from the excited state's rovibrational state to the ground-state separated atom limit via other unstable excited states.…”

Thirty years of density functional theory in computational chemistry: an overview and extensive assessment of 200 density functionals

“…A recent study by Truhlar et al [227] concluded that CCSD(T) should not be used as a reference to validate density functionals, which complicates the proper benchmarking of density functionals for transition metal chemistry. Very recently, however, two studies [228,229] demonstrated that CCSD(T) can be reliably used for the prediction of transition metal bond dissociation energies. Nevertheless, it is important to verify that the best functionals resulting from this study are capable of handling transition metals with reasonable accuracy, since the database utilised thus far is entirely composed of main-group elements.…”

Predicting Ligand-Dissociation Energies of 3d Coordination Complexes with Auxiliary-Field Quantum Monte Carlo

“…[31][32][33][34][35] However, the reliability of CC methods for transition metal systems, even when multireference effects are approximated, has been the subject of vigorous debate, as illustrated by recent studies on transition metal diatomic-ligand systems. 24,[36][37][38][39][40][41] de Oliveira-Filho and co-workers found that even multireference CCSD(T) could not predict the bond dissociation energies (BDEs) for some diatomics accurately with respect to experimental measurements. A recent study by Head-Gordon and co-workers found that high levels of CC, up to CCSDTQ, are required for chemical accuracy against an exact method known as Adaptive Sampling Configuration Interaction (ASCI) results, albeit in a small basis set.…”