Structure and magnetic properties of nitroxide molecular crystals by density functional calculations employing periodic boundary conditions.

The structure and magnetic properties of one-dimensional chains of representative nitroxides have been studied by a density functional model employing periodic boundary conditions. The optimized geometries are in better agreement with experiments 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 electron spin resonance experiments. Magnetic couplings computed by the broken symmetry approach reproduce the ferro- or antiferromagnetic behavior of different nitroxides derived from experiments. These results point out the reliability of the computational model and the significant tuning of all the magnetic properties by intermolecular hydrogen bridges.