Novel ground state structures of N-doped LuH₃

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• High-pressure hydride superconductors are crucial for scientific discovery.
• Ab-initio crystal structure searches are key to identifying new materials.

Purpose of the Study:

• Predict novel ground state structures for N-doped LuH3 at ambient conditions.
• Investigate the electronic properties and bonding characteristics of these structures.
• Clarify the role of nitrogen doping in LuH3's electronic behavior.

Main Methods:

• Evolutionary crystal structure searches were employed.
• Electronic density of states, electronic localization functions, and Bader charge analyses were performed.
• Calculations were conducted for various N-doped LuH3 compositions.

Main Results:

• A novel insulating ground state structure was predicted for LuN0.125H2.875 (∼1.0 wt.% N), persisting up to 45 GPa.
• Metallic behavior was observed for an H-deficient variant.
• Insulators exhibit both H+ and H- ions, while metals only show H- ions.
• A direct correlation between N-H bond formation and insulating behavior was identified.
• Ground states for higher N-content compositions were also found to be insulating.

Conclusions:

• N-doping in LuH3 can lead to insulating ground states at ambient conditions, contrary to prior metallic assumptions.
• The formation of covalent N-H bonds is directly linked to the insulating nature of these materials.
• These findings offer new insights into the design of novel hydride materials.