1. Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren’ai Road, Suzhou 215123, P. R. China
2. Department
of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
3. Center
for Computational Materials Science, Department of Complex Physical
Systems, Institute of Physics, Slovak Academy of Sciences, SK-84511 Bratislava, Slovakia