Comments on MESO-m3c-mod

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	Comments on MESO-m3c-mod

The atom-atom model for ion-pair formation described and discussed in this module plays a central role in the articles in the first part of the corpus. In the various original articles, the model is given partially. We have grouped all information concerning the model in this mesoscopic module, so that in the modularised version, each article only has to contain a brief indication of the model, in addition to a link to this module.
In this module the restrictions of the atom-atom model are discussed. This entire discussion is lifted from A03 [Baede and Los; 1971]
In the original article A05, the terms adiabatic and diabatic states, and adiabatic and diabatic transitions were used. This terminology, is rather common in the domain of chemical physics, leads to confusion. The confusion is, for example, apparent in the term `pseudo-crossing': the crossing of the potential curves in the diabatic representation of the electronic states that is forbidden in the adiabatic representation; [#!O'Malley!#] cautions that this term is``nonsensical''. In this mesoscopic module, we prefer to describe the configurations as covalent and ionic and the transitions are covalent-ionic, covalent-covalent or ionic-ionic.