At the time when increasing numbers of chemists are being attracted by the fascination of supposedly easy computing and associated colourful imaging, this book appears as a counterpoint. The first part focuses on fundamental concepts of quantum chemistry, covering MCSCF theory, perturbation treatments, basis set developments, density matrices, wave function instabilities to correlation effects, and momentum space theory. The second part is devoted to more practical studies, ranging from the characterisation of exotic interstellar molecules, the accurate determination of spectroscopic constants, excited states structures and EPR parameters through photochemical and charge-transfer processes, cluster chemistry and fullerenes, muonium chemistry, to the possible prediction of the response of materials to electric fields in view of nonlinear optical applications. Audience: Graduate students and researchers whose work involves quantum chemistry, molecular physics, and materials modelling.

Quantum mechanical calculations in physics, chemistry and biology are widely recognized as useful interpretative and predictive tools. Unfortunately, they are plagued by unfavorable convergence limitations due to the use of finite linear combinations of basis functions. With the current computer technologies, there is a possible way out to the situation by solving numerically the corresponding wave equations. The present interest and need for numerical determination of electronic structure of atoms, diatomic and poly atomic molecules led us to organize a NATO-ARW devoted to these questions. The aim of the meeting was to provide a review of the state of the art about techniques and applications. The organizing committee consisted of Drs. G. Berthier, P. Claverie, M. Defranceschi, J. Delhalle, H.J. Monkhorst and P. Pyykk6. It was a great sorrow for us to be informed in January 88 of the death of Professor P. Claverie who supported so enthusiastically the idea of having such a meeting organized. The NATO Advanced Research Worshop on : " Numerical Determination of the Electronic Structure of Atoms, Diatomic and Poly atomic Molecules" was held at Versailles (France) from April 17th till April 22th, 1988.

The goal of this volume is to bring together experts on numerical analysis, computer science and chemistry and produce homogenous contributions on ab initio quantum chemistry. The papers from the different communities collected in this volume are written in a language to be comprehensible to the others. This volume is of interest to applied mathematicians and quantum chemists.

Quantum mechanical calculations in physics, chemistry and biology are widely recognized as useful interpretative and predictive tools. Unfortunately, they are plagued by unfavorable convergence limitations due to the use of finite linear combinations of basis functions. With the current computer technologies, there is a possible way out to the situation by solving numerically the corresponding wave equations. The present interest and need for numerical determination of electronic structure of atoms, diatomic and poly atomic molecules led us to organize a NATO-ARW devoted to these questions. The aim of the meeting was to provide a review of the state of the art about techniques and applications. The organizing committee consisted of Drs. G. Berthier, P. Claverie, M. Defranceschi, J. Delhalle, H.J. Monkhorst and P. Pyykk6. It was a great sorrow for us to be informed in January 88 of the death of Professor P. Claverie who supported so enthusiastically the idea of having such a meeting organized. The NATO Advanced Research Worshop on : " Numerical Determination of the Electronic Structure of Atoms, Diatomic and Poly atomic Molecules" was held at Versailles (France) from April 17th till April 22th, 1988.

At the time when increasing numbers of chemists are being attracted by the fascination of supposedly easy computing and associated colourful imaging, this book appears as a counterpoint. The first part focuses on fundamental concepts of quantum chemistry, covering MCSCF theory, perturbation treatments, basis set developments, density matrices, wave function instabilities to correlation effects, and momentum space theory. The second part is devoted to more practical studies, ranging from the characterisation of exotic interstellar molecules, the accurate determination of spectroscopic constants, excited states structures and EPR parameters through photochemical and charge-transfer processes, cluster chemistry and fullerenes, muonium chemistry, to the possible prediction of the response of materials to electric fields in view of nonlinear optical applications. Audience: Graduate students and researchers whose work involves quantum chemistry, molecular physics, and materials modelling.