A Survey by the Editors.- I.1 Violation of the Noncrossing Rule: The Hubbard Hamiltonian for Benzene.- I.2 Two Theorems on the Hubbard Model.- I.3 The Hubbard Model: Some Rigorous Results and Open Problems.- I.4 Flux Phase of the Half-Filled Band.- II.1 Proof of the Peierls Instability in One Dimension.- II.2 Stability of the Peierls Instability for Ring Shaped Molecules.- III.1 A Model for Crystallization: A Variation on the Hubbard Model.- III.2 Phase Separation due to Quantum Mechanical Correlations.- IV.1 Theory of Ferromagnetism and the Ordering of Electronic Energy Levels.- IV.2 Ordering Energy Levels of Interacting Spin Systems.- IV.3 Magnetic Properties of Some Itinerant-Electron Systems at T > 0.- V.1 Phase Transitions in Reservoir-Driven Open Systems with Applications to Lasers and Superconductors.- V.2 Equilibrium Statistical Mechanics of Matter Interacting with the Quantized Radiation Field.- V.3 Constructive Macroscopic Quantum Electrodynamics.- V.4 The Laser: A Reversible Quantum Dynamical System with Irreversible Classical Macroscopic Motion.- VI.1 A Proof of Part of Haldane's Conjecture on Spin Chains.- VI.2 Rigorous Results on Valence-Bond Ground States in Antiferromagnets.- VI.3 Valence Bond Ground States in Isotropic Quantum Antiferromagnets.- VI.4 Ground State Properties of a Fully Frustrated Quantum Spin System.- VII.1 Exact Ground State Energy of the Strong-Coupling Polaron.- VIII.1 Simplified Approach to the Ground-State Energy of an Imperfect Bose Gas.- VIII.2 Bose-Einstein Quantum Phase Transition in an Optical Lattice Model.- VIII.3 The Quantum-Mechanical Many-Body Problem: The Bose Gas.- Some of the Early History of Exactly Soluble Models.- IX.1 Exact Solution of the Problem of the Entropy of Two-Dimensional Ice.- IX.2 Exact Solution of the F Model of an Antiferroelectric.- IX.3 Exact Solution of the Two-Dimensional Slater KDP Model of a Ferroelectric.- IX.4 Residual Entropy of Square Ice.- IX.5 Two-Dimensional Ferroelectric Models.- IX.6 Relations Between the 'Percolation' and 'Colouring' Problem and Other Graph-Theoretical Problems Associated with Regular Planar Lattices: Some Exact Results for the 'Percolation' Problem.- IX.7 Analytic Properties of the Free Energy for the Ice Models.- X.1 Two-Dimensional Ising Model as a Soluble Problem of Many Fermions.- X.2 Solution of the Dimer Problem by the Transfer Matrix Method.- XI.1 Two Soluble Models of an Antiferromagnetic Chain.- XII.1 Exact Analysis of an Interacting Bose Gas. I. The General Solution and the Ground State.- XII.2 Exact Analysis of an Interacting Bose Gas. II. The Excitation Spectrum.- XIII.1 Delta-Function Fermi Gas with Two-Spin Deviates.- XIII.2 Absence of Mott Transition in an Exact Solution of the Short-Range, One-Band Model on One Dimension.- XIV.1 Exact Solution of a Many-Fermion System and Its Associated Boson Field.- Selecta of Elliott H. Lieb.- Publications of Elliott H. Lieb.
A Survey by the Editors.- I.1 Violation of the Noncrossing Rule: The Hubbard Hamiltonian for Benzene.- I.2 Two Theorems on the Hubbard Model.- I.3 The Hubbard Model: Some Rigorous Results and Open Problems.- I.4 Flux Phase of the Half-Filled Band.- II.1 Proof of the Peierls Instability in One Dimension.- II.2 Stability of the Peierls Instability for Ring Shaped Molecules.- III.1 A Model for Crystallization: A Variation on the Hubbard Model.- III.2 Phase Separation due to Quantum Mechanical Correlations.- IV.1 Theory of Ferromagnetism and the Ordering of Electronic Energy Levels.- IV.2 Ordering Energy Levels of Interacting Spin Systems.- IV.3 Magnetic Properties of Some Itinerant-Electron Systems at T > 0.- V.1 Phase Transitions in Reservoir-Driven Open Systems with Applications to Lasers and Superconductors.- V.2 Equilibrium Statistical Mechanics of Matter Interacting with the Quantized Radiation Field.- V.3 Constructive Macroscopic Quantum Electrodynamics.- V.4 The Laser: A Reversible Quantum Dynamical System with Irreversible Classical Macroscopic Motion.- VI.1 A Proof of Part of Haldane's Conjecture on Spin Chains.- VI.2 Rigorous Results on Valence-Bond Ground States in Antiferromagnets.- VI.3 Valence Bond Ground States in Isotropic Quantum Antiferromagnets.- VI.4 Ground State Properties of a Fully Frustrated Quantum Spin System.- VII.1 Exact Ground State Energy of the Strong-Coupling Polaron.- VIII.1 Simplified Approach to the Ground-State Energy of an Imperfect Bose Gas.- VIII.2 Bose-Einstein Quantum Phase Transition in an Optical Lattice Model.- VIII.3 The Quantum-Mechanical Many-Body Problem: The Bose Gas.- Some of the Early History of Exactly Soluble Models.- IX.1 Exact Solution of the Problem of the Entropy of Two-Dimensional Ice.- IX.2 Exact Solution of the F Model of an Antiferroelectric.- IX.3 Exact Solution of the Two-Dimensional Slater KDP Model of a Ferroelectric.- IX.4 Residual Entropy of Square Ice.- IX.5 Two-Dimensional Ferroelectric Models.- IX.6 Relations Between the 'Percolation' and 'Colouring' Problem and Other Graph-Theoretical Problems Associated with Regular Planar Lattices: Some Exact Results for the 'Percolation' Problem.- IX.7 Analytic Properties of the Free Energy for the Ice Models.- X.1 Two-Dimensional Ising Model as a Soluble Problem of Many Fermions.- X.2 Solution of the Dimer Problem by the Transfer Matrix Method.- XI.1 Two Soluble Models of an Antiferromagnetic Chain.- XII.1 Exact Analysis of an Interacting Bose Gas. I. The General Solution and the Ground State.- XII.2 Exact Analysis of an Interacting Bose Gas. II. The Excitation Spectrum.- XIII.1 Delta-Function Fermi Gas with Two-Spin Deviates.- XIII.2 Absence of Mott Transition in an Exact Solution of the Short-Range, One-Band Model on One Dimension.- XIV.1 Exact Solution of a Many-Fermion System and Its Associated Boson Field.- Selecta of Elliott H. Lieb.- Publications of Elliott H. Lieb.
Commentaries.- A Survey by the Editors.- I. Thermodynamic Limit for Coulomb Systems.- I. 1 Existence of Thermodynamics for Real Matter with Coulomb Forces.- I. 2 The Constitution of Matter: Existence of Thermodynamics for Systems Composed of Electrons and Nuclei.- II. Hard Sphere Virial Coefficients.- II. 1 Suppression at High Temperature of Effects Due to Statistics in the Second Virial Coefficient of a Real Gas.- II. 2 Calculation of Exchange Second Virial Coefficient of a Hard-Sphere Gas by Path Integrals.- III. Zeros of Partition Functions.- III. 1 Monomers and Dimers.- III. 2 Theory of Monomer-Dimer Systems.- III. 3 A Property of Zeros of the Partition Function for Ising Spin Systems.- III. 4 A General Lee-Yang Theorem for One-Component and Multicomponent Ferromagnets.- IV. Reflection Positivity.- IV. 1 Existence of Phase Transitions for Anisotropic Heisenberg Models.- IV. 2 Phase Transitions in Anisotropic Lattice Spin Systems.- IV. 3 Phase Transitions in Quantum Spin Systems with Isotropic and Nonisotropic Interactions.- IV. 4 Phase Transitions and Reflection Positivity. I. General Theory and Long Range Lattice Models.- IV. 5 Phase Transitions and Reflection Positivity. II. Lattice Systems with Short-Range and Coulomb Interactions.- IV. 6 Lattice Models for Liquid Crystals.- IV. 7 Existence of Neel Order in Some Spin-1/2 Heisenberg Antiferromagnets.- IV. 8 The XY Model Has Long-Range Order for all Spins and all Dimensions Greater than One.- V. Classical Thermodynamics.- V. 1 The Third Law of Thermodynamics and the Degeneracy of the Ground State for Lattice Systems.- V. 2 A Guide to Entropy and the Second Law of Thermodynamics.- V. 3 A Fresh Look at Entropy and the Second Law of Thermodynamics.- VI. Lattice Systems.- VI. 1 Properties of a Harmonic Crystal in a Stationary Nonequilibrium State.- VI. 2 The Statistical Mechanics of Anharmonic Lattices.- VI. 3 Time Evolution of Infinite Anharmonic Systems.- VI. 4 Lattice Systems with a Continuous Symmetry III. Low Temperature Asymptotic Expansion for the Plane Rotator Model.- VII. Miscellaneous.- VII. 1 The Finite Group Velocity of Quantum Spin Systems.- VII. 2 The Classical Limit of Quantum Spin Systems.- VII. 3 A Refinement of Simon's Correlation Inequality.- VII. 4 Fluxes, Laplacians, and Kasteleyn's Theorem.- Selecta of Elliott H. Lieb.- Publications of Elliott H. Lieb.
The Hubbard model is a `highly oversimplified model' for electrons in a solid which interact with each other through extremely short-ranged repulsive (Coulomb) interaction. The Hamiltonian of the Hubbard model consists of two parts: which describes quantum mechanical hopping of electrons, and which describes non-linear repulsive interaction. Either or alone is easy to analyse, and does not favour any specific order. But their sum is believed to exhibit various non-trivial phenomena including metal-insulator transition, antiferromagnetism, ferrimagnetism, ferromagnetism, Tomonaga-Luttinger liquid, and superconductivity. It is believed that we can find various interesting `universality classes' of strongly interacting electron systems by studying the idealized Hubbard model. In the present article we review some mathematically rigorous results relating to the Hubbard model which shed light on the `physics' of this fascinating model. We mainly concentrate on the magnetic properties of the model in its ground states. We discuss the Lieb-Mattis theorem on the absence of ferromagnetism in one dimension, Koma-Tasaki bounds on the decay of correlations at finite temperatures in two dimensions, the Yamanaka-Oshikawa-Affleck theorem on low-lying excitations in one dimension, Lieb's important theorem for the half-filled model on a bipartite lattice, Kubo-Kishi bounds on the charge and superconducting susceptibilities of half-filled models at finite temperatures, and three rigorous examples of saturated ferromagnetism due to Nagaoka, Mielke, and Tasaki. We have tried to make the article accessible to non-experts by giving basic definitions and describing elementary materials in detail.
Exact results for interface structure and wetting functional relations for sl(3) Chiral Potts model at q2=-1 facet shapes in a Wulff Crystal macroscopic description of phase separation in the 2D Ising model Peierls instability for the Holstein model Falicov-Kimball models - a partial review of the ground states problem Hubbard model with magnetic field - antiferromagnetism and paramagnetism quantum hall effect without divergence of the localization length on quantum stochastic dynamics for quantum spin systems on a lattice - low temperature problem interface states of quantum spin systems thermodynamic behaviour of the Bogoliubov Weakly imperfect Bose gas sum rules for Coulomb systems with hard cores ground state energy of the low density Bose gas universality and scaling in random matrix models and random polynomials KAM-renormalization-group for Hamiltonian systems with two degrees of freedom on the landscape of attractors in a neural network with interacting patterns potentials for one-dimensional restrictions of Gibbs measures. (Part contents)
A. The Course.- Molecules Coupled to Their Environment.- Theories of Molecular Chirality: A Short Review.- Condensed Cooper Pairs and Macroscopic Quantum Phenomena.- Non-Equilibrium Statistical Mechanics: Dynamics of Macroscopic Observables.- Quantum Brownian Motion.- Localization Critical Exponents.- Stochastic Models of Population and Phase Relaxation.- Classical and Quantum, Lattice and Continuum Percolation.- Tunneling and Relaxation in Low Temperature Systems.- Dynamics of Quantum Particles: Coupled Coherent and Incoherent Motion.- Chaotic Motion of Molecular Chains.- Complex Surface Geometry in Nano-Structure Solids: Fractal versus Bernal-Type Models.- Aggregation Phenomena.- Electrodeposition: Phenomenology and Theory.- Screening in Electrolytes and in Polymer Solutions: The Charge Structure Function.- In Search of Scaling Laws in Porous Silica Gels.- Stochastic Aspects in Reaction Kinetics.- B. The Seminars.- I Quantum Theory of Large Systems.- Coherence and Quantum Mechanics.- The Dynamical Generation of Macroscopic Coherent Light.- Macroscopically Inhomogeneous Bose-Einstein Condensation.- Generalized Squeezing of Boson States.- Equilibrium States of Long-Range Interacting Quantum Lattice Systems.- Environment and Symmetry Breaking in Quantum Field Theory.- Gauge Chemistry.- II Localized and Extended States.- Coherence Effects in Excitation Transfer: Application to Hexagonal Photosynthetic Unit.- Random Matrix Theory and Anderson Localisation.- Local Moments and the Localization of Electrons in Liquids.- How Universal is the Scaling Theory of Localization?.- Dimers, Repulsions, and the Absence of Localisation.- III Transport and Reactions.- Electronic Excitations in Polysilanes: Frenkel Excitons of a Disordered Chain.- The Study of Energy Change in Radical Systems.- Decay From an Initial Unstable State in a Chemical Reaction Model.- The Effects of Static Disorder on Polaron Transport.- Diffusion in a Disordered Line.- Bimolecular Diffuion-Limited Reaction Kinetics at Steady State.- Dynamic Percolation Theory for Diffusion of Interacting Particles: Tracer Diffusion in a Multi-Component Lattice Gas.- Crossover from Dispersive to Diffusive Energy Transport.- The Coupling Scheme for Relaxations in Complex Correlated Systems.- Simulation of Excitation Transport in Disordered Media.- Dynamical Exponents for 1-D Random-Random Directed Walks.- IV Polymers.- Interactions between Poly(styrene-co-styrene Sulfonic Acid) and Poly(methylmethacrylate-co-4-vinyl Pyridine) in Dimethyl Sulfoxide Solution by Photon Correlation Spectroscopy.- Interactions of Sigma Conjugated Polymers With Strong Optical Fields.- Randomly Branched Polymers.- Multi-Particle Relaxation in Electronically Excited Polymers: Distribution of Transition Rates from Fluorescence Data - A Numerical Approach.- Understanding Heat Conduction in Oriented Polymers.- Static Correlations of Polymer Chains in Networks.- Theory of Polymers on Fractal Lattices.- V Disordered and Low-Dimensional Systems.- Self-Consistent Interpretation of Percolation in a Microemulsion.- Experimental Evidence of Fractal Aggregates in Dense Microemulsions.- Fractal Dynamics of the Catalytic CO-Oxydation - Application of Fractal Cellular Automata Models.- Electrodeposition: Fractal and Multifractal Measures.- High Resolution Spectroscopy of Langmuir-Blodgett Films.- Molecular Dynamics Simulation of the Transport of Small Molecules Across a Polymer Membrane.- Reactions in Microemulsions: Fractal Modeling.- Enhanced Membrane Rigidity in Charged Lamellar Phases.- VI Words of thanks.- Lecturers.- Participants.
I Infinite Renormalization of the Hamiltonian Is Necessary.- II Quantum Field Theory Models.- I. The ?22n Model.- Fock space.- Q space.- The Hamiltonian H(g).- Removing the space cutoff.- Lorentz covariance and the Haag-Kastler axioms.- II. The Yukawa Model.- Preliminaries.- First and second order estimates.- Resolvent convergence and self adjointness.- The Heisenberg picture.- III Boson Quantum Field Models.- I. General Results.- Hermite operators.- Gaussian measures and the Schrodinger representation.- Hermite expansions and Fock space.- II. The Solution of Two-Dimensional Boson Models.- The interaction Hamiltonian.- The free Hamiltonian.- Self-adjointness of H(g).- The local algebras and the Lorentz group automorphisms.- IV Boson Quantum Field Models.- III. Further Developments.- Locally normal representations of the observables.- The construction of the physical vaccum.- Formal perturbation theory and models in three space-time dimensions.- V The Particle Structure of the Weakly Coupled P(?)2 Model and Other Applications of High Temperature Expansions.- I. Physics of Quantum Field Models.- Five years of models.- From estimates to physics.- Bound states and resonances.- Phase space localization and renormalization.- VI The Particle Structure of the Weakly Coupled P(?)2 Model and Other Applications of High Temperature Expansions.- II. The Cluster Expansion.- The main results.- The cluster expansion.- Clustering and analyticity: proof of the main results.- Convergence: the main ideas.- An equation of Kirkwood-Salsburg type.- Covariance operators.- Derivatives of covariance operators.- Gaussian integrals.- Convergence: the proof completed.- VII Particles and Bound States and Progess Toward Unitarity and Scaling.- VIII Critical Problems in Quantum Fields.- IX Existence of Phase Transitions for ?24 Quantum Fields.- X Critical Exponents and Renormalization in the ?4 Scaling Limit.- Formulation of the problem.- The scaling and critical point limits.- Renormalization of the ?2(x) field.- Existence of the scaling limit.- The Josephson inequality.- XI A Tutorial Course in Constructive Field Theory.- e?tH as a functional integral.- Examples.- Applications of the functional integral representation.- Ising, Gaussian and scaling limits.- Main results.- Correlation inequalities.- Absence of even bound states.- Bound on g.- Bound on dm2/d? and particles.- The conjecture ?(6) ? 0.- Cluster expansions.- The region of convergence.- The zeroth order expansion.- The primitive expansion.- Factorization and partial resummation.- Typical applications.
The Hubbard model is a "highly oversimplified model" for electrons in a solid which interact with each other through extremely short ranged repulsive (Coulomb) interaction. The Hamiltonian of the Hubbard model consists of two pieces; H_hop which describes quantum mechanical hopping of electrons, and Hint which describes nonlinear repulsive interaction. Either H_hop or H_int alone is easy to analyze, and does not favor any specific order. But their sum H=H_hop+H_int is believed to exhibit various nontrivial phenomena including metal-insulator transition, antiferromagnetism, ferrimagnetism, ferromagnetism, Tomonaga-Luttinger liquid, and superconductivity. It is believed that we can find various interesting "universality classes" of strongly interacting electron systems by studying the idealized Hubbard model. In the present article we review some mathematically rigorous results on the Hubbard model which shed light on "physics" of this fascinating model. We mainly concentrate on magnetic properties of the model at its ground states. We discuss Lieb-Mattis theorem on the absence of ferromagnetism in one dimension, Koma-Tasaki bounds on decay of correlations at finite temperatures in two-dimensions, Yamanaka-Oshikawa-Affleck theorem on low-lying excitations in one-dimension, Lieb's important theorem for half-filled model on a bipartite lattice, Kubo-Kishi bounds on the charge and superconducting susceptibilities of half-filled models at finite temperatures, and three rigorous examples of saturated ferromagnetism due to Nagaoka, Mielke, and Tasaki. We have tried to make the article accessible to nonexperts by describing basic definitions and elementary materials in detail.