iQual: a new computer program for qualitative phase analysis with efficient search–match capability

iQual is a new computer program developed for qualitative phase analysis using powder diffraction data. It is based on a new database named Crystal_db, derived from the latest Crystallography Open Database. Crystal_db has been created with organized functional modules and optimized index structures, greatly enhancing the database's search efficiency. The iQual program offers users a wide range of querying capabilities and convenient visualization features. In addition to providing an efficient interactive interface, the program combines with the optimized database to enable efficient searching for and finding of the data entries that best match the experimental data for qualitative analysis of X-ray diffraction patterns. The highlight of this search–match method lies in an effective two-step approach that makes full use of the database structure. A preliminary screening is adopted, based on the five strongest diffraction peaks of each candidate phase, prior to scoring the candidate phases. Matrix operations in both screening and scoring processes enhance the program's efficiency.