The subject of this book intermolecular interactions is as important in physics as in chemistry and molecular biology. Intermolecular interactions are responsible for the existence of liquids and solids in nature. They determine the physical and chemical properties of gases, liquids, and crystals, the stability of chemical complexes and biological compounds. In the first two chapters of this book, the detailed qualitative description of different types of intermolecular forces at large, intermediate and short-range distances is presented. For the first time in the monographic literature, the temperature dependence of the dispersion forces is discussed, and it is shown that at finite temperatures the famous Casimir-Polder asymptotic formula is correct only at narrow distance range. The author has aimed to make the presentation understandable to a broad scope of readers without oversimplification. In Chapter 3, the methods of quantitative calculation of the intermolecular interactions are discussed and modern achievements are presented. This chapter should be helpful for scientists performing computer calculations of many-electron systems. The last two chapters are devoted to the many-body effects and model potentials. More than 50 model potentials exploited for processing experimental data and computer simulation in different fields of physics, chemistry and molecular biology are represented. The widely used global optimisation methods: simulated annealing, diffusion equation method, basin-hopping algorithm, and genetic algorithm are described in detail. Significant efforts have been made to present the book in a self-sufficient way for readers. All the necessary mathematical apparatus, including vector and tensor calculus and the elements of the group theory, as well as the main methods used for quantal calculation of many-electron systems are presented in the appendices.

The subject of this book -- intermolecular interactions is as important in physics as in chemistry and molecularbiology. Intermolecular interactions are responsible for theexistence of liquids and solids in nature. They determine thephysical and chemical properties of gases, liquids, and crystalsthe stability of chemical complexes and biological compounds.In the first two chapters of this book, the detailed qualitativedescription of different types of intermolecular forces at largeintermediate and short-range distances is presented. For the firsttime in the monographic literature, the temperature dependence ofthe dispersion forces is discussed, and it is shown that at finitetemperatures the famous Casimir-Polder asymptotic formula iscorrect only at narrow distance range. The author has aimed to makethe presentation understandable to a broad scope of readers withoutoversimplification. In Chapter 3, the methods of quantitativecalculation of the intermolecular interactions are discussed andmodern achievements are presented. This chapter should be helpfulfor scientists performing computer calculations of many-electronsystems.The last two chapters are devoted to the many-body effects andmodel potentials. More than 50 model potentials exploited forprocessing experimental data and computer simulation in differentfields of physics, chemistry and molecular biology are represented.The widely used global optimisation methods: simulated annealingdiffusion equation method, basin-hopping algorithm, and geneticalgorithm are described in detail.Significant efforts have been made to present the book in aself-sufficient way for readers. All the necessary mathematicalapparatus, including vector and tensor calculus and the elements ofthe group theory, as well as the main methods used for quantalcalculation of many-electron systems are presented in theappendices.

Preface.1 Background Knowledge.1.1 The Subject and its Specificity.1.2 A Brief Historical Survey.1.3 The Concept of Interatomic Potential and AdiabaticApproximation.1.4 General Classification of Intermolecular Interactions.References.2 Types of Intermolecular Interactions: QualitativePicture.2.1 Direct Electrostatic Interactions.2.2 Resonance Interaction.2.3 Polarization Interactions.2.4 Exchange Interaction.2.5 Retardation Effects in Long-Range Interactions and theInfluence of Temperature.2.6 Relativistic (Magnetic) Interactions.2.7 Interaction Between Macroscopic Bodies.References.3 Calculation of Intermolecular Interactions.3.1 Large Distances.3.2 Intermediate and Short Distances.References.4 Nonadditivity of Intermolecular Interactions.4.1 Physical Nature of Nonadditivity and the Definition ofMany-Body Forces.4.2 Manifestations of Nonadditive Effects.4.3 Perturbation Theory and Many-Body Decomposition.4.4 Many-Body Effects in Atomic Clusters.4.5 Atom-Atom Potential Scheme and Nonadditivity.References.5 Model Potentials.5.1 Semiempirical Model Potentials.5.2 Determination of Parameters in Model Potentials.5.3 Reconstructing Potentials on the Basis of ExperimentalData.5.4 Global Optimization Methods.References.Appendix 1: Fundamental Physical Constants and ConversionTable of Physical Units.Appendix 2: Some Necessary Mathematical Apparatus.A2.1 Vector and Tensor Calculus.A2.1.1 Definition of vector; the addition law.A2.1.2 Scalar and vector products; triple scalar product.A2.1.3 Determinants.A2.1.4 Vector analysis; gradient, divergence and curl.A2.1.5 Vector spaces and matrices.A2.1.6 Tensors.A2.2 Group Theory.A2.2.1 Properties of group operations.A2.2.2 Representations of groups.A2.2.3 The permutation group.A2.2.4 The linear groups. The three-dimensional rotationgroup.A2.2.5 Point groups.A2.2.6 Irreducible tensor operators. Spherical tensors.References.Appendix 3: Methods of Quantum-Mechanical Calculations ofMany-Electron Systems.A3.1 Adiabatic Approximation.A3.2 Variational Methods.A3.2.1 Self-consistent field method.A3.2.2 Methods taking into account the electron correlation.A3.2.2.1 r12-dependent wave functions.A3.2.2.2 Configuration interaction.A3.2.2.3 Coupled cluster method.A3.2.2.4 Density functional theory approach.A3.3 Perturbation Theory.A3.3.1 Rayleigh-Schr¨odinger perturbation theory.A3.3.2 Møller-Plesset perturbation theory.A3.3.3 Operator formalism and the Brillouin-Wignerperturbation theory.A3.3.4 Variational perturbation theory.A3.3.5 Asymptotic expansions; Padé approximants.References.Index.