Geometrical structures of Cr doped and Cu-Cr co-doped 32-atoms supercell of AlN were optimized with first principles density functional based on full potential augumented plane waves and generalized gradient approximation (GGA). Lattice constant, band structure, electronic density and optical properties were calculated. It indicates that Cr-doped and Cu-Cr co-doped AlN are both half metallic, their band gaps become narrower. Cu-Cr co-doped AlN system has stronger spin polarization effect than Cr doped, and exhibits fine ferromagnetic. Range of optical absorption becomes broader with doping. Co-doping enhances long-wave absorption and energy loss decreases obviously.

Geometrical structure of Ag doped 32-atom super-cell of AlN was optimized with first principle density functional theory based on full potential linearized augumented plane wave method. Electronic structures,magnetic and optical properties were calculated and discussed in detail. It shows that Ag doping makes Ag4 d electrons hybrid with its nearest neighbor N2 p electrons,which introduces impurity bands to form acceptor energy level and realizes p-type doping. The system enhances its conductivity and shows metallic and weak magnetism. Its net magnetic moment is 1.38 μ_в. Mulliken charge population of N-Ag bonds through Ag doping is small and bonds show strong ionic bonding properties. Imaginary part of dielectric function and optical absorption spectrum of the doping system show a new peak in low energy region. Complex refractive index function changes in low energy region. And absorption edge extends to low energy. Doping system enhances long-wave absorption and energy loss decreases obviously.