The Sixth Annual Conference of the Center for Nonlinear Studies at the Los Alamos National Laboratory was held May 5-9, 1986, on the topic "Nonlinearity in Condensed Matter: Lessons from the Past and Prospects for the Future. " As conference organizers, we felt that the study of non­ linear phenomena in condensed matter had matured to the point where it made sense to take stock of the numerous lessons to be learned from a variety of contexts where nonlinearity plays a fundamental role and to evaluate the prospects for the growth of this general discipline. The successful 1978 Oxford Symposium on nonlinear (soliton) struc­ ture and dynamics in condensed matter (Springer Ser. Solid-State Sci. , Vol. 8) was held at a time when the ubiquity of solitons was just begin­ ning to be appreciated by the condensed matter community; in subsequent years the soliton paradigm has provided a rather useful framework for in­ vestigating a large number of phenomena, particularly in low-dimensional systems. Nevertheless, we felt that the importance of nonlinearity in wider arenas than "solitonics" merited a significant expansion in the scope of the conference over that of the 1978 symposium. Indeed, many of the lessons are quite general and their potential for cross-fertilization of otherwise poorly connected disciplines was certainly one of the prime motivations for this conference. Thus, while these proceedings contain many contribu­ tions pertaining to soliton behavior in different contexts, the reader will find much more as well, particularly in the later chapters.

Inhalt

I Historical Perspective.- Nonlinearity: Historical and Technological View.- II Low-Dimensional Magnetism.- Soliton Dynamics: Experiments on Magnetic Chains.- Soliton Dynamics in One-Dimensional Antiferromagnets.- One-Dimensional Easy-Plane Magnets: Classical Sine-Gordon Theory or a Quantum Model?.- Towards a Quantitative Theory of Solitons in One-Dimensional Magnets: Quantum Effects, Out-of-Plane Fluctuations and the Specific Heat.- Quantum Corrections to the Specific Heat of the Easy-Plane Ferromagnetic Chain.- Monte Carlo Calculations of Quantum Systems.- III Conducting Polymers.- Photogeneration of Nonlinear Excitations in Semiconducting Polymers: Fast Response Nonlinear Optical Phenomena.- When Kinks are not Elementary Excitations.- Phonons and Soliton Diffusion in Polyacetylene.- Ground State Properties of Polyacetylene with Off-Diagonal Random Disorder.- IV Experimental Techniques.- Neutron Scattering Studies of Non-Linear Systems.- Novel Experimental Techniques and Realizations of Quasi-Periodicity.- Heavy-Electron Materials.- Magnetic Resonance as a Probe of Nonlinearity in Condensed Matter Physics.- High-Resolution He Beam Scattering as a Tool for the Investigation of the Structural and Dynamical Properties of Surface Soliton Dislocations.- V Theoretical Techniques.- Quantum Mechanics at the Macroscopic Level.- Soluble Models.- Variational Schemes for Many-Electron Systems.- Quantum Monte Carlo.- Quantum Spin Chains and Conformally Invariant Non-Linear ?-Models.- Collective Coordinates and Linear Modes of the Double-Sine-Gordon Kink.- A Collective Coordinate Method for Classical Dynamics of Nonlinear Klein-Gordon Kinks.- Quantum Coherence and the Nonlinear Schrödinger Equation.- Energy Transfer, Self-Trapping, and Solitons on a Nonlinear Dimer.- VI Structural Phase Transitions.- Microscopic Probing of BaTiO3 Ferroelectric Phase Transitions by EPR.- Structural Transformations in DNA.- Phonon Anomalies, Structural Transformations, and Precursor Structure in the Martensitic Alloys TiNi(Fe) and Al1?xNix.- Temperature Dependence of the Soft Mode for Structural Phase Transitions in Highly Anisotropic Systems.- A Model for the B?Z Transition of DNA Involving Solitary Excitations.- VII Spin-Glasses and Random Field Systems.- Recent Experimental Results in Spin-Glass Dynamics.- Spin Glasses: Recent Theoretical Developments.- The Random Field Problem - Facts and Fiction.- Statics and Dynamics of the Random Field Ising Model (Theory).- A Driven Random Field System: CDW Dynamics.- VIII Frustrated, Incommensurate, and Nonequilibrium Systems.- Topography and Diffusion of Kinks in Incommensurate Insulators: Relationship Between Phase Conjugation and Thermal Hysteresis in Incommensurate Phases, and a Physical Analog for Circadian Biorhythms.- Model of Icosahedral Order.- Systematics of Disorder in Quasiperiodic Material.- Friction and Forced Flow: Collective Transport in Disordered Media.- Non-Equilibrium Behavior, Hysteresis and Condensate Quakes in the Pinned Charge Density Wave.- Vortex Dynamics in Two-Dimensional Arrays of Superconducting Weak Links.- Interfacial Pattern Formation: A Progress Report.- Intrinsic Defect States in Protein Assemblages.- Is Universality Valid on Hierarchical and Fractal Lattices?.- IX Summary.- Lessons from the Past and Prospects for the Future?.- Index of Contributors.