In the OPP approach, every atom is treated as an individual Einstein oscillator subject to Boltzmann statistics in the classical limit. The OPP itself represents the potential as experienced by an atom at a certain position and allows, e.g., to assess the viability and activation barriers of migration pathways [see K. N. Trueblood, H.-B. Bürgi, H. Burzlaff, J. D. Dunitz, C. M. Gramaccioli, H. H. Schulz, U. Shmueli, S. C. Abrahams, Acta Crystallogr., Sect. A: Found. Crystallogr. 1996, 52, 770–781; H. Boysen, Z. Kristallogr. 2003, 218, 123–131].
JANA2006, one of the standard programs in powder and single-crystal diffractometry, readily calculates sections of probability-density functions (PDFs) in 2D. However, it does only allow for the derivation of the resulting one-particle potential (OPP) in 1D, i.e., along a pathway within one section. This problem is overcome by this program, which can read the output from JANA2000/JANA2006 and calculate a 2D OPP map in a format fit for plotting. It can also reformat the PDF input and handle error maps.