X-ray phase determination by the principle of minimum charge

Area of Science:

• Crystallography
• Materials Science
• Computational Chemistry

Background:

• Electron density reconstruction from Fourier modes is crucial for understanding crystal and quasicrystal structures.
• The global minimum value of electron density is highly sensitive to the relative phases of Fourier modes.

Purpose of the Study:

• To investigate the relationship between electron density, total charge, and phase determination in crystalline and quasicrystalline systems.
• To explore if minimizing electronic charge can enhance the atomicity and resolution of reconstructed electron densities.

Main Methods:

• Utilizing the principle that maximizing the global minimum density corresponds to minimizing total electronic charge.
• Applying charge minimization techniques to simulated crystalline and quasicrystalline diffraction data.

Main Results:

• Phases that minimize total electronic charge lead to degenerate and proliferating minima in electron density.
• Minimizing electronic charge forces density maxima into smaller, more localized regions, enhancing atomicity.
• The charge minimization method successfully reproduced correct phases from random initial phases for both crystal and quasicrystal data.

Conclusions:

• Minimizing electronic charge is an effective strategy for resolving phase ambiguities in electron density reconstruction.
• This approach enhances the atomicity of electron density, leading to improved structural characterization of crystals and quasicrystals.