THE CURRENT IN MAGNETIC-FIELD DENSITY-FUNCTIONAL THEORY AND ITS APPLICATION TO THE CHEMICAL SHIELDING AND MAGNETIC-SUSCEPTIBILITY

A gradient expansion of the electronic current in the electron density is used to obtain expressions for the magnetic susceptibity and chemi cal shielding. The first term in the expansion is the Thomas Fermi exp ression. All succeeding terms diverge for both properties. A renormali zed functional is used which removes the divergences and gives asympto tic diamagnetism. A single parameter which depends linearly on the num ber of electrons gives all heavy rare gas susceptibities to within 1% of exact calculation using the same electron density, Similar results are found for the chemical shielding. Susceptibility and shielding cal culations for the helium dimer and the hydrogen molecule in singlet an d triplet states are presented. The results are compared with other ca lculations over a full range of internuclear distances. (C) 1997 Ameri can Institute of Physics.