Theoretical study of the thermodynamic parameters of (CaO)(n) nanoclusters with n=2-16 in the gas and solution phases: proton affinity, molecular basicity, and pK(b) values

摘要

Thermodynamic quantities such as proton affinity (PA) and molecular basicity (GB) for (CaO)(n) nanoclusters with n = 2-16 have been calculated using three computational models of the density functional theory (DFT) (Becke, 3-parameter, Lee-Yang-Parr (B3LYP), Minnesota 2006, Perdew-Wang 1991 (PW91), Coulomb attenuated method-B3LYP, and omega B97XD functionals); Moller-Plesset perturbation theory; and Hartree-Fock with the cc-PVNZ (n = D and T) basis set in the gas phase. Absolute deviation error (AAD%) indicates that obtained PA and GB values using DFT model and the B3LYP method with mean percentage errors of 0.77 and 0.90%, respectively, have the higher accuracy than the other methods and models. The values obtained for the proton affinity and gas-phase basicity of the nanoclusters were compared to experimental data reported in the literature. In order to confirm basicity properties, quantum descriptors of the molecular electrostatic potential (MEP) and valence natural atomic orbital energies (NAO) have been computed. The MEP and NAO values for species under probe display excellent correlation coefficient. The polarizable continuum model for investigating the solvents effect of water, DMSO, and benzene on the basicity of the CaO nanoclusters has been applied.