Nonlinear characteristics of structural properties and spontaneous polarization in wurtzite MgxZn1-xO: A first-principles study

First-principles calculations were carried out on the basis of the density functional theory to investigate the structural properties and spontaneous polarization in wurtzite MgxZn1-xO. Random atomic configurations were applied to compute electronic ground states in large 4 x 4 x 3 unit cells containing 192 atoms. Our theoretical calculation predicted a nonlinear characteristic of the lattice parameters a, c, and u of wurtzite MgxZn1-xO, indicating the violation of Vegard's law. We also clarified a nonlinear characteristic of spontaneous polarization in the alloys and its almost linear dependence on the internal parameter u.