This book comprises the Proceedings of a NATO Advanced Study Institute on Mu1ticritica1 Phenomena held in Geilo, Norway, between 10-21 April 1983. This school was the seventh to be held in Gei10, on various aspects of phase transitions. In spite of its apparently restrictive title the school was planned as a forum for the discus­ sion of phase transitions and instabilities in systems, with competing interactions and competing order parameters. Thus, in addition to the canonical multicritical points, subjects were diverse as critical phenomena in random magnetic systems and routes to chaos were discussed. The subject matter of the school is naturally divided into a series of categories which to some extent, reflect the historical development of interest in competing phenomena at phase transitions. Multicritical points in equilibrium systems, defined phenomenolo­ gically as points of sudden change of behaviour on an otherwise smooth phase boundary, were the first topics of the school. The theo­ retical consensus which has emerged during the past decade, largely as a result of calculations with the renormalisation group, was reviewed in some detail. The results presented, however, apply only to pure systems (in which dirt and other manifestations of reality are irrelevant) in that small realm close to the phase transition knoYln as "asymtopia.

Multicriticality: A theoretical Introduction.- Partial Differential Approximants for Multicritical Singularities: An Overview.- Experimental Studies of Magnetic Tricritical Points: Problems and Progress.- Experimental Studies of Bicritical Points in 3D Antiferromagnets.- The Experimental Evidence for a Lifshitz Point in MnP.- Nature of the Smectic-A-Smectic-C Transition near a Nematic-Smectic-A-Smectic-C Multicritical Point.- Dynamics near Multicritical Points.- Critical Dynamics of Sound.- Multicritical Phenomena at Structural Phase Transitions.- Bi- and Tetra-critical Behaviour of Uniaxially Stressed LaA103.- Fluctuation Driven Multicritical Points.- A New Multicritical Point in A Seven Dimensional Parameter Space.- Multicritical Points in Incommensurate Systems.- Neutron Investigation of Modulated Structures.- Nature of The Incommensurate Phase in Rb2ZnCl4.- New Phenomena in Incommensurate Barium Sodium Niobate: Memory and Relaxation Effects.- Critical Fluctuations and Magnetic Ordering in Praseodymium Metal.- Soft Mode and Central Peak as A Consequence of Competing Interactions.- Criticality and Crossover in Structural Phase Transitions.- Anomalous Vibrational Absorption Near the Antiferro-electric Phase Transition in Alkali Cyanides.- A Plenitude of Commensurate Phase in Simple Models.- Commensurability, Chaos and The Devil's Staircase.- The Complete Devil's Staircase and Universality of Mode Locking Structures in Discrete Mappings.- Low Temperature Analysis of the ANNNI Model in A Field.- Field Behaviour of Spin Models with Competing Interactions.- Phase Transitions in Crystals with Competing Interactions.- Commensurate Melting and Domain Walls in Surface Phases.- The Role of Domain Walls in The Critical Behaviour of the Three-Dimensional p-State AsymmetricClock Model.- Interfacial Adsorption in Multi-State Models.- Vortex Pinning in Thin Superfluid Films.- Theory of Critical Phenomena in Random Systems.- Critical Behaviour of Disordered Ising Systems: Supression of The Specific Heat Divergence at Tc.- Disorder, Random Fields and Competing Interactions in Antiferromagnets.- The Origin and Influences of The Spin-Glass Problem.- Phase (?) Transitions in Systems with Spin Glass and Long-Range Order Regimes.- Time Effects of The Field Cooled Magnetization of A Au (Fe) Spin Glass.- Spin Glasses: Recent Theoretical Developments.- Critical and Multicritical Points, Lines and Surfaces of Spin Glasses in The Presence of Magnetic Fields and Anisotropy.- Some Renormalization Group Results on the Quenched Gauge Field Model of The Spin Glass.- Frustration, Landau Levels and Superconducting Diamagnetism on Networks.- to Chaos: Phenomenon, Structure of Spectra and Diffusion.- Multicritical Behaviour of A Nonequilibrium System.- Participants.