G Factors of Conduction Electrons in Metals.

A new ab initio fully relativistic method for the calculation of conduction-electron g factors in metals is presented. The g factors at points on the Fermi surface have been evaluated as the matrix elements of the relativistic magnetic moment operator with the wave functions of the fully relativistic linear muffin-tin orbital method in the atomic sphere approximation. The orbital g _{c} factors have been deduced and compared with experimental data for principal orbits on the Fermi surfaces of alkali, noble and platinum-group transition metals. Previous theoretical approaches to g factor calculations have been carefully analyzed and it has been concluded that the usual scalar-relativistic LMTO method, where both spin-orbit interaction and the Zeeman operators are included as a first-order perturbation, neglects contributions which can be significant in heavier noble and transition metals. Some particular examples of the breakdown of perturbation theory include the neck orbit in gold, the central Gamma 6 orbit in platinum and the X hole pocket orbits in iridium. A comparison with experimental g factor data for noble metals makes it possible to estimate the exchange -correlation enhancement factor. The Fermi-surface average of the enhancement factor exhibits weak anisotropy, in agreement with the prediction of first-principles calculations. Experimental data for transition metals prove to be insufficiently accurate to yield reliable values for the exchange-correlation enhancement factor.