On nuclear quadrupole interaction “families”

Abstract

Nuclear quadrupole interactions (NQIs) of systems which are closely related often exhibit non-trivial linear correlations among the components of the electric field gradient tensor (EFG) with the most frequent implicit parameter being temperature. In the language of “families” this corresponds to one and the same member of the “family” at different “stages”. However, systems with identical nearest neighbours at fixed bond distances but variable bond angles — regardless what the reason for that might be — can also constitute a “family”. Moreover, systems with fixed bond distances and angles but variable occupation numbers of electron orbitals — including the addition/deletion of a bond — can constitute “families” as well. In this article the prerequisites for observing such linear correlations among EFG tensor components are discussed within a point charge model and ilustrated by examples. It will be pointed out whenever conclusions can be drawn which are valid beyond the point charge model. In addition, a new way of analysing nuclear quadrupole interaction data which exhibit linear correlations among EFG tensor components is presented.