Effect of the surroundings on atomic and molecular properties

Abstract

Abstract This review is concerned with three types of physical phenomena which are affected by the environment of the species under study. They are the vibrational spectrum, nonlinear optical properties, and nuclear magnetic shielding of the molecule (or atom) of interest. The two types of environment discussed are liquid solvents and zeolite cages. The emphasis is on the theoretical-calculational aspects but experimental studies will also be referred to wherever appropriate. The primary objective is to bring under one wing these different phenomena and environments. To give two examples: the methods used to evaluate the vibrational spectrum of a molecule trapped in a zeolite cage should bear some relation to the chemical shift of an atom trapped in the zeolite; the effects of a solvent on a species' nonlinear optical properties (e.g. second harmonic generation) should be understandable in the same way as the effects on the species' vibrational spectrum and magnetic shielding constants. Both perturbation-theoretic and ab initio variational methods are employed in describing what has been accomplished and a general, but brief, discussion of how electric fields behave in solutions is given. Most of the calculations reviewed are far from the accuracy of their gas phase counterparts and it is realized that, in the subject of this article, many questions remain unanswered and that there is often little consensus about the best approach to take for the problem at hand. A bringing-together of the topics reviewed may shed some light. The references selected are not exhaustive but it is hoped that they are sufficient to illuminate the author's primary goal.