Maximum-likelihood density modification

Journal Article · Tue Aug 01 04:00:00 EDT 2000 · Acta Crystallographica. Section D: Biological Crystallography

DOI:https://doi.org/10.1107/S0907444900005072· OSTI ID:22347924

A likelihood-based density modification approach is developed that can incorporate expected electron-density information from a wide variety of sources. A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ▶), Acta Cryst. D55, 1863–1871].

• OSTI ID: 22347924
• Journal Information: Acta Crystallographica. Section D: Biological Crystallography, Journal Name: Acta Crystallographica. Section D: Biological Crystallography Journal Issue: Pt 8 Vol. 56; ISSN ABCRE6; ISSN 0907-4449
• Country of Publication: Denmark
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DENSITY
ELECTRON DENSITY
ELECTRONS
MODIFICATIONS
PROBABILITY
SOLVENTS
STRUCTURE FACTORS
YIELDS