THE ELECTRONIC G-TENSOR OF MGF - A COMPARISON OF ROHF AND MRD-CI LEVEL RESULTS

Despite their importance in the characterization of molecular magnetis m, electronic g-tensors have received rather little theoretical attent ion. fn this work, however, the ground-state g-tensor of MgF is comput ed at both the ROHF and multireference CI levels. The calculations are expanded complete to second order in appropriate Breit-Pauli terms an d the contributions of all important magnetically coupled excited stat es are accounted for. Both the CI- and ROHF-level Delta g(parallel to) -values (- 59 and - 55 ppm, respectively) are in agreement with experi ment (- 319 +/- 500 ppm) within the range of experimental uncertainty. For Delta g (perpendicular to), however, the ROHF treatment yields a value (- 659 ppm) in substantial disagreement with experiment (- 1319 +/- 500 ppm). Fortunately, this discrepancy is alleviated by CI level treatment (Delta g (perpendicular to) = - 1447 ppm). (C) 1996 John Wil ey & Sons, Inc.