Extrapolation of Atomic Natural Orbitals of basis set to complete basis set limit

Relativistic Atomic Natural Orbitals (ANO-RCC) are extrapolated to the complete basis set limit. ANO-RCC-VXZP (X = D, T, Q) basis sets were extrapolated using standard extrapolation techniques. Five noncovalent complexes, characterized by hydrogen, dispersion and halogen interactions, were chosen. Accurate description of the studied complexes is allowed only after the inclusion of electron correlation and large basis sets which have to include polarization and diffuse functions. Results are in quantitative agreement with the benchmark data obtained by standard aug-cc-pVXZ-DK (X = D, T, Q) basis sets considering chemical accuracy of ±1 kcal/mol.

Nucleophilicity Index Based on Atomic Natural Orbitals

A simple method of evaluating a semilocal (regional) nucleophilicity is introduced. The concept involves use of the natural orbitals for atomic populations to identify the most “reactive population” of electrons on particular atom in molecule. The results of test calculations considering the regioselectivity problem in electrophilic aromatic substitution to the benzene derivatives are presented and briefly discussed.