Electron Correlations in Molecules and Solids [Paperback]

Dieser Titel verbindet die Festk?rpertheorie mit der Quantenchemie. Neue Konzepte der Vielteilchen-Verarbeitung und Korrelations-Effekte, normale quantenchemische Verfahren mit Projektionstechniken, Greensche Funktionen und Monte-Carlo-Methoden werden erarbeitet. Anwendungsbereiche der Molek?ltheorie, von Halbleitern, supraleitender high-Tc-Materialien, etc., werden vorgestellt.Electron Correlations in Molecules and Solids bridges the gap between quantum chemistry and solid-state theory. In the first half of the text new concepts are developed for treating many-body and correlation effects, combining standard quantum chemical methods with projection techniques, Greens-function methods and Monte-Carlo techniques. The second half deals with applications of the theory to molecules, semiconductors, transition metals, heavy-fermion systems, and the new high-Tc superconducting materials.1. Introduction.- 2. The Independent-Electron Approximation.- 2.1 Starting Hamiltonian.- 2.2 Basis Functions and Basis Sets.- 2.3 Self-Consistent Field Approximation.- 2.4 Simplified SCF Calculational Schemes.- 2.4.1 Semi-empirical SCF Methods.- 2.4.2 Pseudopotentials.- 2.5 Koopmans Theorem.- 2.6 Homogeneous Electron Gas.- 2.7 Local Exchange Potential  The Xa Method.- 2.8 Shortcomings of the Independent-Electron Approximation.- 2.9 Unrestricted SCF Approximation.- 3. Density Functional Theory.- 3.1 Thomas-Fermi Method.- 3.2 Hohenberg-Kohn-Sham Theory.- 3.3 Local-Density Approximation.- 3.4 Results for Atoms, Molecules, and Solids.- 3.5 Extensions and Limitations.- 4. Quantum-Chemical Approach to Electron Correlations.- 4.1 Configuration Interactions.- 4.1.1 Local and Localized Orbitals.- 4.1.2 Selection of Double Substitutions.- 4.1.3 Multireference CI.- 4.2 Many-Body Perturbation Theory.- 5. Cumulants, Partitioning, and Projections.- 5.1 Cumulant Representation.- 5.1.1 Ground-State Energy.- 5.1.2 Perturbation Expansion.- 5.2 Projection and Partitionlóä