1John-von-Neumann Institute for Computing Forschungszentrum Juelich, D-52425 Juelich, Germany
2Department of Physics Centre for Nonlinear Studies and The Beijing–Hong Kong–Singapore Joint Centre for Nonlinear and Complex Systems (Hong Kong) Hong Kong Baptist University Kowloon Tong, Hong Kong, China
3Department of Physics University of Houston Houston, Texas 77204-5005, USA