PASCal is a simple web-based tool that enables rapid and straightforward calculation of the principal coefficients of thermal expansion and compressibilities from variable-pressure/-temperature lattice parameter data. On the one hand, this will allow users to screen easily for anomalous mechanical responses—e.g., NTE, NLC and pressure-induced softening. On the other hand, the reporting of principal axes means that any such effects can be related back to the underlying crystal structure. (See the paper below for some analysis of the MOF Cu-SIP-3, the explosive HMX and the mineral malayaite). The program is of greatest direct benefit when analysing structural changes in monoclinic or triclinic crystals, where the principal axes are not normally coincident with the crystal axes.

While we are aware that PASCal replicates some functionalities of existing excellent codes, it is our hope that the straightforward input format, web accessibility, and ease of output interpretation will help promote the use of orthogonal strain calculations.

The program was written by Matt Cliffe. We hope to have a user manual available online shortly. If there are any ways in which we can make the program easier to use for you, or if you have any suggestions for modifications, please don’t hesitate to contact Andrew or Matt.


>> PASCal: A principal-axis strain calculator for thermal expansion and compressibility determination. J Appl Cryst 45, 1321-1329 (2012)

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