Advanced perspectives in the EXPO software for solving crystal structures from powder diffraction data

Abstract

Innovative computational and graphical tools have been implemented for advancing the crystal structure solution process from powder diffraction data using the EXPO software. These improve the capacity of EXPO to tackle challenging solution cases and make the structural study of microcrystalline materials more user friendly. The novel features concern the structure solution both in reciprocal space and in direct space. For reciprocal-space solution, the new capability to solve an unknown structure from a mixture composed of one unknown structure and one or more phases with known structures is particularly valuable. For direct-space structure solution, EXPO has been enhanced by parallelized simulated annealing with the aim of both reducing the execution time of the solution process and providing a successful result when several degrees of freedom must be varied. Many other new tools, functional for overcoming practical difficulties usually encountered during the solution process, have also been completed. In particular, a new tool for searching and importing structures from the Crystallography Open Database is effective for supporting the solution process in direct space. The advances in EXPO aim to provide software with improved reliability, expanded operation and greater speed.