Incorporating particle symmetry into orientation determination in single-particle imaging

Area of Science:

• Coherent X-ray diffraction imaging
• Crystallography
• Particle physics

Background:

• X-ray diffraction imaging (CDI) experiments record diffraction patterns from identical particles.
• Particles are injected into X-ray free-electron laser (XFEL) beams in random orientations.
• Determining particle orientation is crucial for 3D structure reconstruction but challenging for symmetric particles.

Purpose of the Study:

• To adapt the correlation-maximization method for handling symmetric particles in CDI.
• To enable accurate determination of relative orientations for symmetric particles.
• To utilize correlation maps for symmetry element identification and 3D reconstruction.

Main Methods:

• Modification of the correlation-maximization method to account for particle symmetry.
• Application of the modified method to analyze X-ray diffraction patterns from symmetric particles.
• Utilizing correlation maps to identify symmetry elements and their orientations.

Main Results:

• The modified correlation-maximization method successfully determined relative orientations of symmetric particles.
• Correlation maps revealed the inherent symmetry of the particles.
• The C factor, adapted for symmetric cases, indicated the consistency of the 3D intensity distribution.

Conclusions:

• The adapted correlation-maximization method is effective for orienting symmetric particles in CDI.
• This technique facilitates the determination of symmetry elements and aids in 3D structure reconstruction.
• The modified C factor provides a reliable measure of data consistency for symmetric particle assemblies.