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First-principles calculations on solid nitrogen: A comparative study of high-pressure phases

Kotakoski, J. and Albe, K. (2008):
First-principles calculations on solid nitrogen: A comparative study of high-pressure phases.
In: Phys. Rev. B, American Physical Society, p. 144109, 77, (14), [Online-Edition: http://prb.aps.org/abstract/PRB/v77/i14/e144109],
[Article]

Abstract

There is experimental evidence that nitrogen forms a polymeric solid under pressure. In this study, we compare various solid nitrogen phases by means of ab initio calculations based on density-functional theory to describe solid nitrogen at different pressures. We show that two phases with covalent bonds in all three dimensions are energetically the most favored at pressures of 50-200 GPa and that the layered black phosphorus phase becomes lower in enthalpy at pressures exceeding 200 GPa, at least at low temperatures. However, according to our results, black phosphorus is unstable at pressures close to 200 GPa. We further present band structure and density of states calculations for the relevant known phases at several pressures and show that black phosphorus is metallic when metastable, whereas the lower-pressure phases remain dielectric with pressure-dependent band gaps. Also the questionable experimental relevance of several of the previously proposed structures is addressed.

Item Type: Article
Erschienen: 2008
Creators: Kotakoski, J. and Albe, K.
Title: First-principles calculations on solid nitrogen: A comparative study of high-pressure phases
Language: English
Abstract:

There is experimental evidence that nitrogen forms a polymeric solid under pressure. In this study, we compare various solid nitrogen phases by means of ab initio calculations based on density-functional theory to describe solid nitrogen at different pressures. We show that two phases with covalent bonds in all three dimensions are energetically the most favored at pressures of 50-200 GPa and that the layered black phosphorus phase becomes lower in enthalpy at pressures exceeding 200 GPa, at least at low temperatures. However, according to our results, black phosphorus is unstable at pressures close to 200 GPa. We further present band structure and density of states calculations for the relevant known phases at several pressures and show that black phosphorus is metallic when metastable, whereas the lower-pressure phases remain dielectric with pressure-dependent band gaps. Also the questionable experimental relevance of several of the previously proposed structures is addressed.

Journal or Publication Title: Phys. Rev. B
Volume: 77
Number: 14
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 28 Feb 2012 14:46
Official URL: http://prb.aps.org/abstract/PRB/v77/i14/e144109
Identification Number: doi:10.1103/PhysRevB.77.144109
Related URLs:
Funders: This work has been supported by Deutsche Forschungsgemeinschaft through Project No. AL 578/3-1., We also acknowledge financial support through a program funded by the German foreign exchange server �DAAD� and the Academy of Finland
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