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Title: Asymmetric band flipping for time-of-flight neutron diffraction data

Journal Article · · Journal of Applied Crystallography (Online)
 [1];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
  2. 72 Cedar Street, Brisbane (Australia)

Charge flipping with powder diffraction data is known to produce a result more reliably with high-resolution data,i.e.visible reflections at smalldspacings. This data are readily accessible with the neutron time-of-flight technique but the assumption that negative scattering density is nonphysical is no longer valid where elements with negative scattering lengths are present. The concept of band flipping was introduced in the literature, where a negative threshold is used in addition to a positive threshold during the flipping. But, it was not tested with experimental data at the time. Finallly, band flipping has been implemented inTOPAStogether with the band modification of low-density elimination and tested with experimental powder and Laue single-crystal neutron data.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1327598
Journal Information:
Journal of Applied Crystallography (Online), Vol. 49, Issue 5; ISSN 1600-5767
Publisher:
International Union of CrystallographyCopyright Statement
Country of Publication:
United States
Language:
English

References (8)

Ab initio reconstruction of difference densities by charge flipping journal November 2010
Direct-space methods in phase extension and phase determination. I. Low-density elimination journal July 1992
Ab initio structure solution by charge flipping journal March 2004
Ab initio neutron crystallography by the charge flipping method journal February 2007
Cross-Linked Layered Structure of Magnetically Ordered [Fe(TCNE)2]⋅z CH2Cl2 Determined by Rietveld Refinement of Synchrotron Powder Diffraction Data journal February 2007
The charge flipping algorithm journal December 2007
A charge-flipping algorithm incorporating the tangent formula for solving difficult structures journal August 2007
Cross-Linked Layered Structure of Magnetically Ordered [Fe(TCNE)2]⋅z CH2Cl2 Determined by Rietveld Refinement of Synchrotron Powder Diffraction Data journal February 2007