SPECIAL ISSUE IN HONOUR OF JOHN MAIER A new algorithm to characterise the degree of concaveness of a molecular surface relevant in ion mobility spectrometry

A new algorithm to describe the convex or concave nature of the surface of a given molecular structure was developed and incorporated into the projected superposition approximation (PSA). The new method searches for a reference structure characterised by a minimal surface area fully enclosing the molecule. The ratio of the molecular surface area to the surface area of this reference structure was found to be a good descriptor of the molecular concaveness required for the accurate calculation of theoretical cross sections using PSA. These computations are an essential step in the interpretation of ion mobility data in terms of ion molecular structure.