1. Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
2. Research Institute of Industrial Science and Technology, Pohang 37673, Republic of Korea
3. Department of Physics & Astronomy and Center for Computational Sciences, Mississippi State University, Mississippi State, Mississippi 39762, United States
4. Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea