Journal of Chemical Physics, Vol.105, No.4, 1460-1469, 1996
Coupled Hartree-Fock Calculations of Molecular Magnetic-Properties Annihilating the Transverse Paramagnetic Current-Density
The reliability of the continuous transformations of origin of the current density method, which makes the transverse paramagnetic current vanish (CTOCD-PZ), for the prediction of nearly gauge-origin independent molecular magnetic susceptibility and gauge-origin independent nuclear magnetic shielding, is proved on the basis of a fairly large number of calculations, It is shown that, within the computational scheme provided by the coupled Hartree-Fock perturbation theory (CHF), convergence towards the presumed Hartree-Fock limit, for magnetic susceptibility and proton magnetic shielding, is systematically reached using basis sets which are smaller than those required by conventional common origin and CTOCD-DZ techniques. For second-row nuclear magnetic shieldings a variant of the CTOCD-PZ method, which shifts the origin of the current towards the nearest nucleus for points close to nuclei, as suggested originally by Keith and Bader with the CSDGT method [T. A. Keith and R. F. W. Bader, Chem. Phys. Lett. 210, 223 (1993)], gives likewise good results with affordable basis sets.
Keywords:ORIGIN INDEPENDENT CALCULATIONS;NMR SHIELDING CONSTANTS;CHEMICAL-SHIFTS;BASIS-SETS;GAS-PHASE;CONTINUOUS TRANSFORMATION;LOCALIZED QUANTITIES;ELECTRON CORRELATION;FUNCTIONAL THEORY;BONDED MOLECULES