Calculation of the EPR g-Tensors of High-Spin Radicals with Density Functional Theory

Abstract

The second-order DFT approach of Schreckenbach and Ziegler to the computation of EPR g tensors of doublet radicals (J. Phys. Chem. A 1997, 101, 3388), has been generalized to arbitrary spatially nondegenerate electronic states. The new technique is applied to a large number (47) of diatomic main-group radicals, in nΣ (n > 2) ground states. Calculated principal components, of the EPR g tensors, are in a good agreement with experiment for main group radicals, with the average errors approaching the accuracy available in experimental matrix isolation studies (VWN average absolute error: 3.8 ppt). The agreement with experiment deteriorates for the mixed, main group−transition metal radicals (VWN error: 8.1 ppt) but the major trends in Δg⊥ values are still reproduced. The approach largely breaks down for radicals containing chemical bonds between two transition metal atoms (VWN error: 30 ppt). In all cases, the calculated g tensors are insensitive to the choice of the approximate exchange-correlation functi...