Electronic structure and thermochemistry for monocarbides MC, MC+ and MC− (M=Zn, Cd, Hg): CCSD(T) and DFT works

Abstract

In this work, the ab-initio coupled cluster CCSD(T) method and the B3LYP, BP91W and CAM-B3LYP functional of DFT method in conjunction with the aug-cc-pVTZ-PP basis have been applied to study the group 12 monocarbides MC, MC+ and MC−. The potential energy curves (PECs) for the three electronic states 3Σ−, 5Σ− and 1Δ of the MC and the two states 2∑- and 4∑- for the MC+ cations and MC− anions have been investigated. In addition, Bond distance Re, transition energy Te, vibrational frequency ωe, ionization energy IE, electron affinity EA, dipole moment μ, dissociation energy D0 and heat formation ΔH°f0/ΔH°f298, were determined for each species. The analysis of the dissociation energy for ZnC, CdC and HgC shows the decrease in the stability of the monocarbides from Zn to Hg. For ΔH°f0/ΔH°f298 values of MC, which are not known experimentally or theoretically, we recommend the following CCSD(T) predictions of ZnC, CdC and HgC: 181.3/178.54, 180.65/178.4 and 175.35/174.71 kcal/mol respectively. Comparing the three functionals with the CCSD(T) results, the CAM-B3LYP functional shows excellent predictive agreement for the various properties of the group 12 monocarbides.