Plesio

Plesio is a software package for the analysis and characterisation of plesiotwins, oriented crystal associations based on a coincidence-site lattice usually larger, and often much larger, than that found in twins. The theory and the software description are he objects of two articles published in April 2026:

• Coincidence-Site Lattice (CSL) investigation in the analysis of plesiotwinning. I. Theory. Journal of Applied Crystallography, 59, 609-622 , https://doi.org/10.1107/S1600576726001135;
• Coincidence-Site Lattice (CSL) investigation in the analysis of plesiotwinning. II. PLESIO software.. Journal of Applied Crystallography, 59, 623-630 https://doi.org/10.1107/S1600576726001147 .

The installer can be downloaded from this link. It contains all the necessary files (executable, libraries, user manual etc.). Run it by double-click the .msi file; it proposes to install the software in the C:\Plesio folder, but you have the choice to change the destination folder. Do NOT however choose the Program Files folder, otherwise the software will probably not run correctly, because it does not have the rights to write the output files in that folder.