1. Department of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand, Department of Molecular Dynamics/Computer Simulation, Faculty of Physics and Geosciences, Institute for Theoretical Physics (ITP), University of Leipzig, Augustusplatz 10-11, 04109 Leipzig, Germany, and Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand