diff*gif => density plot of time dependence of one-particle density of 
time evolution state for the \alpha_1 case


parameters in file name:
diffus_dens_<delta_t>_<N>_<U>_<U_R>_<\lambda>.gif

with delta_t=time step for one pixel in vertical direction, 
t=iteration time, N=system size, U=interaction strength, 
U_R=interaction range, \lambda=lambda parameter of Harper model
