546-1Within the framework of multi-configurational self-consistent field (MCSCF) approximation, the ground and excited states of the N 4 (D 2H ) cluster of N 2 molecules are modeled from different initial states. The potential barriers to the cluster formation and dissociation are calculated. Investigations of the N 4 (D 2H ) electronic spectrum demonstrate that the most promising method of forming nitrogen nanostructures is compression of the excited triplet N 2 molecules.

We analyze the possibility of the nanoscale phase separation manifesting itself in the formation of ferromagnetic (FM) polarons (FM droplets) in the general situation of doped anisotropic three-and two-dimensional antiferromagnets. In these cases, we calculate the shape of the most energetically favorable droplets. We show that the binding energy and the volume of a FM droplet in the three-dimensional (3D) case depend only upon two universal parametersJ = (Jx + Jy + Jz)S 2 and t ef f = (txtytz) 1/3 , whereJ and t ef f are effective antiferromagnetic (AFM) exchange and hopping integrals, respectively. In the two-dimensional (2D) case, these parameters have the form J = (Jx + Jy)S 2 and t ef f = (txty) 1/2 . The most favorable shape of a ferromagnetic droplet corresponds to an ellipse in the 2D case and to an ellipsoid in the 3D case.