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Z. Naturforsch. 69a, 619 – 628
(2014)
doi:10.5560/ZNA.2014-0062
Theoretical Calculations of Mechanical, Electronic, and Chemical Bonding in CaN2, SrN2, and BaN2
1 College of Physical Science and Technology, Sichuan University, Chengdu 610064, China
2 Department of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
3 National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China
Received January 3, 2014 / revised May 8, 2014 / published online November 5, 2014
Reprint requests to: Y. C.; E-mail:
ycheng@scu.edu.cn
We present a first-principles density functional theory-based study about the impact of pressure on the structural and elastic properties of bulk CaN2, SrN2, and BaN2. Non-spin and spin polarized calculations indicate that the non-spin polarized ground state was more favourable with magnetic moments of 1.049 μB, 1.059 μB, and 1.014 μB for CaN2, SrN2, and BaN2, respectively, and these were in good agreement with previous experimental and theoretical data. The high bulk modulus of CaN2, SrN2, and BaN2 confirm that those compounds have low compressibility and high hardness. The obtained bulk modulus, N–N bond length, and optimized structure parameters are
similar to those from previous studies. With an increase in applied pressure the independent elastic constants of CaN2, SrN2, and BaN2 indicated the presence of mechanical instability at 20, 15, and 10 GPa, which is possibly related to phase transitions in addition to a decrease in N–N bond length.
Key words: Density Functional Theory; Elastic Constants; Electronic Structure; Alkaline Earth Diazenides.