DFT description of the magnetic structure of polynuclear transition-metal clusters

Broken symmetry B3LYP-DFT calculations on three- and four-spin systems, namely the complexes [{Cu(bpca)(2)(H2O)(2)}{Cu(NO3)(2)}(2)], (bpca = Bis(2-pyridylcarbonyl)amine), 1, and [Cu(DBSQ)(C2H5O)](2), (DBSQ = 3,5-di-tert-butyl-semiquinonato), 2, have been performed. A procedure to compute the exchange coupling constants through the use of a complete set of broken symmetry determinants is suggested. (C) 2004 Wiley Periodicals, Inc.