Phase Transitions from Saddles of the Potential Energy Landscape

The relation between saddle points of the potential of a classical many-particle system and the analyticity properties of its thermodynamic functions is studied. For finite systems, each saddle point is found to cause a nonanalyticity in the Boltzmann entropy, and the functional form of this nonanal...

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Bibliographic Details
Published in:arXiv.org 2007-07
Main Authors: Kastner, Michael, Schnetz, Oliver, Schreiber, Steffen
Format: Article
Language:English
Subjects:
Mathematical analysis
Particles
Phase transitions
Potential energy
Saddle points
Saddles
Online Access:Get full text
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Summary:The relation between saddle points of the potential of a classical many-particle system and the analyticity properties of its thermodynamic functions is studied. For finite systems, each saddle point is found to cause a nonanalyticity in the Boltzmann entropy, and the functional form of this nonanalytic term is derived. For large systems, the order of the nonanalytic term increases unboundedly, leading to an increasing differentiability of the entropy. Analyzing the contribution of the saddle points to the density of states in the thermodynamic limit, our results provide an explanation of how, and under which circumstances, saddle points of the potential energy landscape may (or may not) be at the origin of a phase transition in the thermodynamic limit. As an application, the puzzling observations by Risau-Gusman et al. on topological signatures of the spherical model are elucidated.
ISSN:2331-8422
DOI:10.48550/arxiv.0703376