Accurate Calculations of Second-Order Electric and Magnetic Properties: Two Ways of Physically Justified Modifications of Basis Sets

EN: Second-order electric and magnetic properties calculated using an approach based upon the simultaneous analytical dependence of the bond order matrix and basis set functions on the corresponding perturbation parameters have been obtained and analyzed for a series of organic molecules. Various methods of selection of basis set quality for different atoms in investigated molecules were examined in conjunction with calculations of 1H NMR chemical shifts. Comparison of the results obtained at different levels of theory (HF, DFT, MP2) demonstrates small correlation effects for polarizability and magnetic susceptibility while the electron correlation effects play crucial role for calculations of nuclear magnetic shielding (chemical shifts).