Development in science depends on several factors. Among these, the role of individual scientists is perhaps not the most important one. Science is typically a body of collective knowledge and any increase in the amount of this knowledge is certainly due to strong interaction among scientists. Even in the past, it happened quite rarely that a single person, without any aid of others, d- covered something fundamental or opened a new chapter in science. Great figures of science history have, in most cases, had rather a summarizing and s- thesizing role. This is especially valid over the last few decades. On one hand, the amount of information necessary to achieve new discoveries, has increased tremendously. On the other hand, improvement of technical facilities has increased the speed of information exchange. These factors resulted in a degree of specialization in science that had never seen before. Most of us are experts and specialists rather than scientists in the classical sense. My personal feeling is that, even nowadays, there is a strong need for professionals with a broad knowledge and c- prehensive mind, although they may not be competitive in the number of their publications or the sizes of their grants. Every time I have met such a person (I can count these cases on my fingers) I have become deeply influenced by his or her strong intellect.

This series presents critical reviews of the present position and future trends in modern chemical research Short and concise reports on chemistry, each written by the world renowned experts Still valid and useful after 5 or 10 years

Klappentext

This volume contains review and research articles in a field of quantum chemical methodology: the theory of electron correlation and the localization problem. Correlation energy (i.e., the energy beyond the Hartree-Fock) plays an important role in the theoretical description of several chemical processes (reactions, excitations, ionization) while localization in quantum chemistry usually emerges as a mathematical transformation of the wave function. The connection between these two issues is provided by the need to evaluate correlation energy for larger molecules, which is much easier in terms of localized contributions. The articles selected discuss copuled cluster, perturbational and geminal-based schemes, and cover wave function as well as density based approaches.

Inhalt
Electron Correlation in Small Molecules: Grafting CI onto CC.- Extremal Electron Pairs Application to Electron Correlation, Especially the R12 Method.- Many-Body Perturbation Theory with Localized Orbitals Kapuy's Approach.- An Introduction to the Theory of Geminals.- Extended Geminal Models.- Ab Initio Modern Valence Bond Theory.- Modern Correlation Theories for Extended, Periodic Systems.- Local Space Approximation Methods for Correlated Electronic Structure Calculations in Large Delocalized Systems that are Locally Perturbed.- Local Electron Densities and Functional Groups in Quantum Chemistry.- Electron Correlation and Reduced Density Matrices.- Localization via Density Functionals.