For instance, we have tried to sort the operators in an ascending order of the amplitudes, or in an ascending or descending order of the absolute value of the amplitudes. It is found that only the amplitude-descending order and the amplitude-absolute-value-descending order can successfully give a 'converged order'. It generally takes 2-5 loops, at most 8 loops for a large value of M (M = 54) to generate a 'converged order'. In contrast, sorting in amplitudeascending order can not reach convergence after 20 loops and doesn't show any signs of convergence.