On: X-ray diffraction from the electron gas in monatomic metallic hydrogen

Area of Science:

• Condensed matter physics
• Materials science
• High-pressure physics

Background:

• Solid hydrogen transitions to a metallic state under extreme compression.
• The X-ray diffraction patterns of metallic hydrogen are not well understood due to its unique electronic structure.

Purpose of the Study:

• To investigate the electron density distributions, atomic motion, and X-ray diffraction intensities of metallic hydrogen phases.
• To determine if X-ray diffraction can be used to identify the crystal structure of monatomic metallic hydrogen.
• To develop tools for analyzing future experimental data.

Main Methods:

• First-principles calculations were employed to model candidate phases of metallic hydrogen.
• Electron density distributions and atomic motions (zero-point and thermal) were computed.
• X-ray diffraction intensities were simulated.

Main Results:

• The electron gas in metallic hydrogen is significantly more structured than predicted by free-electron models.
• Calculated electron densities are more modulated than superpositions of free-atom densities.
• The study demonstrates the fundamental possibility of determining crystal structures from X-ray diffraction data of metallic hydrogen.

Conclusions:

• X-ray diffraction is a viable method for crystal structure determination of monatomic metallic hydrogen.
• An atomic scattering factor was developed to assist in the analysis of experimental diffraction intensities.
• Future experiments could potentially achieve single-crystal diffraction from metallic hydrogen.