1. Department of Electrical and Computer Engineering National University of Singapore 4 Engineering Drive 3 Singapore 117583 Singapore
2. Department of Microstructure School of Physics and Technology Wuhan University Wuhan 430072 China
3. Institute for High Performance Computing A*STAR 1 Fusionopolis Way Singapore 138632 Singapore
4. Department of Physics School of Science Wuhan University of Technology Wuhan 430070 China
5. Institute of Materials Research and Engineering A*STAR 2 Fusionopolis Way Singapore 138634 Singapore