Density Distribution of Bose Condensed Gas in a Three—Dimensional Optical Lattice

For the Bose-condensed gas in a magnetic trap and three-dimensional optical lattice,the non-unifrom distribution of the atoms in different lattice sited in investigated and a propagatro method is used to study the evolution of the interference pattern after the combined potentials are switched off.The analytical result of the wavefunction at any time t is given and especially the motion of the side peaks is described by a simple analytical expression.