Abstract

<jats:p>A multi-purpose pattern-fitting system, RIETAN-2000, has been extensively utilized to
contribute to many structural studies. It offers a sophisticated structure-refinement technique of
whole-pattern fitting based on the maximum-entropy method (MEM) in combination with a MEM
analysis program PRIMA. We have recently completed a successor system, RIETAN-FP, to
RIETAN-2000, adding new features such as standardization of crystal-structure data, an extended
March-Dollase preferred-orientation function, and automation of imposing restraints on bond
lengths and angles. Further, we have been developing a new three-dimensional visualization system,
VESTA, using wxWidgets as a C++ application framework. VESTA excels in visualization, rendering,
and manipulation of crystal structures and electron/nuclear densities determined by X-ray/
neutron diffraction and electronic-structure calculations. VESTA also enables us to display wave
functions and electrostatic potentials calculated with part of these programs.</jats:p>