Structure and Magnetic Properties of Nitroxide Molecular Crystals by Density Functional Calculations Employing Periodic Boundary Conditions

The structure and magnetic properties of 1-dimensional chains of representative nitroxides were studied by a d. functional model employing periodic boundary conditions. The optimized geometries are in better agreement with expts. than those obtained from optimizations of model dimeric systems. The spin populations and isotropic hyperfine couplings compare well with the values measured by polarized neutron and ESR expts. Magnetic couplings computed by the broken symmetry approach reproduce the ferro- or antiferromagnetic behavior of different nitroxides derived from expts. These results point out the reliability of the computational model and the significant tuning of all the magnetic properties by intermol. hydrogen bridges.