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Ab initio structure solution by charge flipping. II. Use of weak reflections
1Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, POB 49, H-1525 Budapest, Hungary. go@szfki.hu
Acta Crystallographica. Section A, Foundations of Crystallography
|December 23, 2004
Summary
A refined charge flipping algorithm enhances X-ray crystallography by treating weak reflections differently. This modification significantly boosts success rates for solving crystal structures ab initio.
Area of Science:
- Crystallography
- Materials Science
- Structural Biology
Background:
- The charge flipping algorithm is a key ab initio method for crystal structure solution using X-ray diffraction data.
- Accurate structure determination is crucial for understanding material properties and biological functions.
Purpose of the Study:
- To present a novel version of the charge flipping algorithm.
- To improve the success rate and applicability of ab initio structure solution.
Main Methods:
- Modified the charge flipping algorithm to treat weak reflections separately.
- Weak reflections' calculated moduli are used unchanged, with phases shifted by pi/2.
- This approach excludes direct use of observed weak reflection data during iteration.
Main Results:
- Achieved significant improvements in structure solution success rates.
- In some cases, success rates increased by a factor of ten.
- Previously unsolvable structures became solvable with the modified algorithm.
Conclusions:
- The modified charge flipping algorithm offers a substantial advancement in ab initio structure solution.
- This enhancement broadens the scope of X-ray crystallography for complex structures.