These two volumes collect forty-four selected papers from the scientific contributions presented at the Third European Workshop on Quantum Systems in Chemistry and Physics, held in Granada (Spain), April 1922, 1998. Ninety-nine scientists from Bulgaria, Columbia, Cuba, Denmark, Finland, France, Germany, Hungary, Israel, Italy, Mexico, Netherlands, Norway, Poland, Russia, Slovakia, Spain, Sweden, United Ki- dom, Uruguay and Venezuela attended the workshop, discussing the state of the art, new trends, and future evolution of the methods and applications. The workshop took place at the 'Los Alixares' Hotel, where 45 lectures were given by prominent members of the scientific community; in addition, 49 posters were presented in two very animated sessions. The success of this workshop is due, without doubt, to the excellent tradition initiated at the previous workshops, organised by Prof. R. McWeeny in San Miniato, Pisa (Italy), 1996, and by Prof. S. Wilson in Oxford (United Kingdom), 1997. These workshops create occasions for meetings and disc- sions on the current state of the art, emerging methods and applications and new trends in this area of science. The three meetings were sponsored and partially supported by the European Union (EU) in the frame of the Cooperation in Science and Technology (COST) chemistry actions.

Inhalt
Response Theory.- Duality in Two-Ways Interferometers: the Symmetric Quanton-Detecton System.- Atomic Resonances in External Fields.- Propagator Calculations for Large Molecules: Determination of Transition Eigenvalues with a Subspace Bisection Method in the Diagonal Algebraic Diagrammatic Construction Approximation.- Accurate Density-Functional Calculation of Core XPS Spectra: Simulating Chemisorption and Intermolecular Effects on Real Systems?.- SCF, CI and DFT Charge Transfers and XPS Chemical Shifts in Fluorinated Compounds.- Condensed Matter.- Diffusion Monte-Carlo Calculations of Quasi-Bound States of Rare Gas-Halogen Clusters: a Diabatic Approach.- Shell-like Features and Charge Localization in Protonated Helium Clusters: a Density Functional Study.- Bond Elongation and Charge Transfer in Diatomic Molecules Interacting with Metal Clusters: H2/Ni and O2/Pt Revisited.- Reactivity at Silicon Surfaces Si(100) 2×2 and Si(111) 7×7.- DFT Modeling of Stark-Tuning Effect: CO on Polarized Pd(100) as a Probe for Double-Layer Electrostatic Effects in Electrochemistry.- Reactive Collisions and Chemical Reactions.- Electro-Nuclear Quantum Mechanics Beyond the Born-Oppenheimer Approximation. Towards a Quantum Electronic Theory of Chemical Reaction Mechanisms.- MCSCF Study of Chemical Reactions in Solution within the Polarizable Continuum Model and VB Analysis of the Reaction Mechanism.- Modeling of the Reaction of Azathioprine with the Hydroxide Anion.- A Theoretical Study of the OH Radical Addition to the Xylenes.- Quantum Molecular Systems in Astrophysics: the Illustrative Example of Interstellar Nitriles and Silanitriles.- Computational Chemistry and Physics.- Discrete Variable Method for Non-Integrable Quantum Systems.- Systematic Truncation of a Distributed UniversalEven-Tempered Basis Set of Gaussian Functions: an Application to the Ground State of the BF Molecule.- N-O and P-O Bond Nature in Hypervalent Compounds: is Bader Analysis Basis-Set and Geometry Independent?.- Hydrogen Bond Between the ?-Hydroxycarboxyl, ?-Hydroxyester and ?-Hydroxyamide Groups: Ab Initio Gas-Phase and Solution Study of a Double Linkage via the Hydroxyl Group.- Theoretical Study of the Proton Affinities of Some Substituted Derivatives of Histamine and Homologous Compounds. Structure-Activity Relationships.