Based on the nonlinear equations of the theory of density wave, the evolutionary direction and the observable conditions on spiral galaxies may be derived by the qualitative analysis theory.

The paper introduces the present knowledge of the theory and technology of diffusion photon density wave (DPDW) which have been focus of the recent research.

The structural stabilities and electronic structures of W atomic chains are studied by employing first-principles plane wave pseudopotential method based on the density functional theory.