Theoretical studies of high-pressure phases, electronic structure, and vibrational properties of NaNH 2

Yan Zhong, Huai Ying Zhou, Chao Hao Hu, Dian Hui Wang, Artem R. Oganov

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Thermodynamically stable phases of sodium amide (NaNH 2) at pressures up to 20 GPa have been determined using the ab initio evolutionary structure prediction. We find that the ground-state phase α-NaNH 2 (orthorhombic, Fddd) first transforms into β-NaNH 2 (orthorhombic, P2 12 12) at 2.2 GPa; then, γ-NaNH 2 (monoclinic, C2/c) becomes stable at 9.4 GPa. In addition to strong ionic bonding between Na + and [NH 2] - ions and covalent bonding between H and N in NH 2 groups, the N-H· · ·N hydrogen bonding between neighboring NH 2 groups could not be ignored anymore in the high-pressure β-NaNH 2, as suggested by the analysis of charge density distribution and structural and vibrational properties. The covalent N-H bonds in the high-pressure phase of NaNH 2 are weakened by additional hydrogen bonding, which could be favorable for the hydrogen desorption.

Original languageEnglish
Pages (from-to)8387-8393
Number of pages7
JournalJournal of Physical Chemistry C
Volume116
Issue number15
DOIs
Publication statusPublished - 19 Apr 2012
Externally publishedYes

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