CALCULATED PARAMAGNETIC-RESONANCE PARAMETERS OF A GALLIUM-ARSENIDE CLUSTER - GA2AS3

Dirac molecular-orbital calculations are reported for the trigonal bip yramid gallium arsenide Ga2As3 cluster, and comparisons are made to el ectron spin resonance spectra. The calculations show good agreement wi th the observed Delta g and Ga-71 hyperfine tensors. This theoretical study predicts both parallel and perpendicular components of the As-75 hyperfine tensors, while experimentally only the perpendicular compon ent was assigned. Furthermore, the calculated isotropic and anisotropi c spin distributions show some discrepancy with the empirically deduce d spin distributions. The discrepancy between the calculated and empir ically deduced values may be traced back to the methodology used in th e empirical treatment. The calculations predict that the single unpair ed electron Spin spend 31.4% of its time on each axial Ga-71 nuclei, a nd, 12.4% of its time on each equatorial As-75 nuclei. (C) 1998 Americ an Institute of Physics.