VALMAP2.0: contour maps using the bond-valence-sum method

VALMAP2.0 is a Microsoft-Windows-based program designed to assist material scientists in accurate structural investigations. The aim of VALMAP is to c alculate the sum of bond valences that a particular atom would have if it w ere placed at any arbitrary point in the crystal. By movement of this atom through all possible points, its valence-sum contour map can be displayed. Parameters of the bond-valence model are available and may be modified. The program was tested in a number of cases and two examples of applications a re reported: (i) finding probable atom sites in crystal structures; (ii) di splacive and order-disorder phase transition mechanisms, analysing steric e ffects.