1. Department of Physics; Capital Normal University; Beijing 100048 China
2. NAAM-Research Group; Department of Mathematics; Faculty of Science; King Abdulaziz University; Jeddah 21589 Saudi Arabia
3. Department of Mathematics; Quaid-I-Azam University; Islamabad 44000 Pakistan
4. Department of Physics; Applied Optics Beijing Area Major Laboratory; Beijing Normal University; Beijing 100875 China