1. Research Centre for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Sector H-12, Islamabad 44000, Pakistan
2. Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan
3. Department of Physics, Faculty of Science, King Saud University, P. O. Box 1846, Riyadh 11321, Saudi Arabia
4. Faculty of Mathematics, University of Cluj, R-3400 Cluj, Romania