1. State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
2. Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, P. R. China
3. European Synchrotron Radiation Facility, ESRF, Grenoble 38043, Cedex 9, France
4. School of Physical Science and Technology, Ningbo University, Ningbo 315211, China