title: Pressure-induced planar N6 rings in potassium azide.
abstract: The first-principles method and the evolutionary algorithm are used to identify stable high pressure phases of potassium azide (KN3). It has been verified that the stable phase with space group I4/mcm below 22 GPa, which is consistent with the experimental result, will transform into the C2/m phase with pressure increasing. These two phases are insulator with N(-)(3) anions. A metallic phase with P6/mmm symmetry is preferred above 40 GPa, and the N atoms in this structure form six-membered rings which are important for understanding the pressure effect on N(-)(3) anions and phase transitions of KN3. Above the studied pressure (100 GPa), a polymerization of N6 rings may be obtained as the result of the increasing compactness.
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, CAS, and Department of Physics, University of Science and Technology of China, Hefei 230031, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: 1] Key Laboratory of Materials Physics, Institute of Solid State Physics, CAS, and Department of Physics, University of Science and Technology of China, Hefei 230031, China [2] Beijing Computational Science Research Center, Beijing 100084, China [3] Kavli Institute for Theoretical Physics China, CAS, Beijing 100190, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Beijing Computational Science Research Center, Beijing 100084, China.
authors.forename: Hai-Qing
authors.initials: HQ
authors.lastname: Lin
authors.affiliation: School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Li