NCNR'S user-friendly rietveld software has wide impact on structure analysis.Rietveld refinement allows crystallographic crys·tal·log·ra·phy
The science of crystal structure and phenomena.
crystal·log analyses to be performed by profile fitting of powder diffraction data. It is widely applied in chemistry, geology, materials science, condensed-matter physics, engineering, and most recently in the life sciences. Use at the NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. neutron source began almost immediately after Hugo Rietveld's seminal paper was published in 1969. The Rietveld technique is of particular value for neutron work, as it offers access to the many advantages of neutron diffraction with short data collection times and without the requirement for large single crystals.
Since the 1970s, three generations of neutron diffraction instrumentation have been built at the NIST Center for Neutron Research (NCNR NCNR NIST Center for Neutron Research
NCNR Non-Cancelable, Non-Returnable
NCNR National Center for Nursing Research (NIH)
NCNR Nearest Common Node Rerouting (ATM)
NCNR National Center for Neutron Research ); the current instrument is the most versatile and highest resolution neutron powder diffractometer A Diffractometer (Main Entry: dif·frac·tom·e·ter Pronunciation: di-"frak-'tä-m&-t&r Function: noun) is a measuring instrument for analyzing the structure of a usually crystalline substance from the scattering pattern produced when a beam of radiation or particles (as X rays or in the United States. During this same period, however, development efforts in Rietveld software lagged behind. This changed significantly when the NCNR developed EXPGUI, a software package to aid users of Los Alamos' General Structure Analysis System (GSAS GSAS Graduate School of Arts and Sciences
GSAS General Structure Analysis System
GSAS Glutamate Gamma-Semialdehyde Synthetase
GSAS Grinnell Students Against Scurvy
GSAS Graduate Students in Arts and Science
GSAS Global Status Accounting System ) package. GSAS is considered to be the most sophisticated and powerful Rietveld package, but it has a very dated command-line user interface that hinders potential users. With EXPGUI, users access GSAS via a modern, user-friendly graphical user interface graphical user interface (GUI)
Computer display format that allows the user to select commands, call up files, start programs, and do other routine tasks by using a mouse to point to pictorial symbols (icons) or lists of menu choices on the screen as opposed to having to .
The EXPGUI software continues to draw thousands of people to the NIST Web site and to sites in Australia, Canada, and England where the EXPGUI Web pages are mirrored. In the past year alone, the EXPGUI documentation and tutorial Web pages were visited more than 100 000 times and the software was downloaded several thousand times.
For further information, see www.ncnr.nist.gov/xtal.
CONTACT: Brian Toby, (301) 975-4297; brian. firstname.lastname@example.org.