Using ab initio evolutionary simulations, we predict the existence of five novel stable Li-N compounds at pressures from 0 to 100 GPa (Li13N, Li5N, Li3N2, LiN2, and LiN5). Structures of these compounds contain of isolated N ions, N2 dimers, polyacetylene-like N chains and N5 rings, respectively. The structure of Li13N consists of Li atoms and Li12N icosahedra (with N atom in the center of the Li12 icosahedron) such icosahedra are notdescribed by Wade-Jemmis electron counting rules and are unique. Electronic structure of Li-N compounds is found to dramatically depend on composition and pressure, making this system ideal for studying metal-insulator transitions. For example, LiN3 undergoes a sequence of pressure-induced transitions: metal-insulator-metal-insulator. This work resolves the previous controversies of theory and experiment on Li2N2.
@article{arxiv.1504.06677,
title = {Novel lithium-nitrogen compounds at ambient and high pressures},
author = {Yanqing Shen and Artem R. Oganov and Guangri Qian and Huafeng Dong and Qiang Zhu and Zhongxiang Zhou},
journal= {arXiv preprint arXiv:1504.06677},
year = {2015}
}