High-level ab initio composites: thermochemical bond dissociation energies for vanadium species

Abstract

Bond dissociation energies (BDE) are among the most sought-after properties in chemistry. Accurate prediction of BDE’s for transition metal species can be daunting for both experiment and computation. Experimental data has been limited and often has large error bars, making the identification of suitable computational methods difficult. Recent advancements in the experimental determination of BDE’s with techniques such as Velocity Map Imaging and 2 Photon Ionisation now provide useful gauges for computational strategies and new methodologies. The vanadium diatomics have been challenging for computational chemistry methods, and, thus, a new experimental gauge enables methods to be reevaluated and developed for these species. Herein, the super-correlation consistent Composite (s-ccCA), a thermochemical scheme centered around CCSD(T)/complete basis set (CBS) limit computations with additional contributions that account for scalar-relativistic effects, and coupled cluster contributions up to quintuple excitations has been considered. The agreement between the s-ccCA scheme and by recent experiments is excellent, demonstrating the utility of the new approach in addressing challenging systems, even those of multireference nature. The longstanding correlation consistent composite approach (ccCA) is also reevaluated for the vanadium species and find that the mean absolute deviation (MAD) is greatly reduced compared to previously used experimental values.