Theoretical study of structural and electronic properties of small GanNn clusters (n=1-10) and their isomers

In this study, structural and electronic properties of GanNn clusters (n=1-10) are investigated using formalism of density functional theory (DFT) and projector augmented plane waves (PAW) within VASP software package. Results of calculations show that more tendency of N atoms in more stable structures of small clusters is the formation of building blocks N2 and  azid, whereas the 3D structures are revealed as cage-like shape with Ga-N bonds. A sharp increase in binding energy per atom from n=1 to n=2 is due to structure transition from 1D to 2D and increase of overlapping between N and Ga orbitals in order to obtain more stability. These changes for clusters with n>3 follow approximately a linear trend. Charge density contour shows an ionic bond with partial covalent character for Ga-N. Also, the lowest energy levels devote to N-s orbitals, middle levels to a hybridized case of Ga-s and N-p orbitals and levels close to Fermi level to a hybridized case of Ga-p and N-p orbitals.