Electronic and Magnetic Properties of Copper Tetraazaporphyrin Influenced by Oxygen - a First-Principles Study

We present the results of the electronic structure calculations for a copper tetraazaporphyrin (CuTAP) model monolayer, both bare and interacting with oxygen. The results are compared with those obtained for copper phthalocyanine. We have found that the CuTAP ferromagnetic configuration is preferred over the paramagnetic one. The calculated value of the magnetic moment of the Cu atom in the CuTAP monolayer is 0.54 mu B. It does not affect strongly the magnetic properties of the monolayer, in which all but pyrrole nitrogen atoms remain unpolarized. The presence of oxygen molecules in the vicinity of the metallic center of the CuTAP causes a decrease in the magnetic moment of Cu, but does not much influence the overall magnetic properties of the monolayer. However, it influences slightly the ground-state electronic structure of the monolayer, mainly due to the charge transfer between the tetraazaporphyrin ring and the O(2) molecules.