Finite nuclear charge density distributions in electronic structure calculations for atoms and molecules

The present review provides comprehensive information on finite nuclear cha rge density distribution models, not only for the purpose of quantum chemic al electronic structure calculations for atoms and molecules, but also for other fields of atomic and molecular physics, A general discussion of the e lectrostatic behaviour of nuclear charge density distributions, spherical o nes and non-spherical ones, is given. A large and reasonably complete set o f spherical finite nucleus models, covering all models widely used in atomi c and nuclear physics, is discussed in detail. Analytic expressions are giv en for charge density distributions, for important radial expectation value s, and for their corresponding electrostatic potentials; these include new material not found in the literature. Thus, the necessary prerequisites for the use of finite nucleus models which are more realistic than the simple, frequently considered models (e.g., the 'homogeneous', 'Gaussian', and Fer mi models) are fulfilled. The use of finite nucleus models in standard quan tum chemical electronic structure programs is briefly reviewed. In order to detect differences between physical properties obtained with various finit e nucleus models. six standardized models were selected to study and compar e energy shifts (non-relativistic and relativistic) in hydrogen-like atoms. It is shown that within this set a clear differentiation of models can be made, not only from the point of View of total energy shifts but also from the point of view of energy differences and in fact even for rather low nuc lear charge numbers. This could be important for future experimental as wel l as theoretical work on hydrogen-like atoms. (C) 2000 Elsevier Science B.V . All rights reserved.