Thermodynamic Instabilities in One Dimension: Correlations, Scaling and Solitons |
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Authors: | Thierry Dauxois Nikos Theodorakopoulos Michel Peyrard |
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Affiliation: | (1) Laboratoire de Physique, UMR-CNRS 5672, ENS Lyon, 46 Allée d'Italie, 69007 Lyon, France;(2) National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, Vasileos Constantinou 48, 116 35 Athens, Greece |
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Abstract: | Many thermodynamic instabilities in one dimension (e.g., DNA thermal denaturation, wetting of interfaces) can be described in terms of simple models involving harmonic coupling between nearest neighbors and an asymmetric on-site potential with a repulsive core, a stable minimum and a flat top. The paper deals with the case of the Morse on-site potential, which can be treated exactly in the continuum limit. Analytical expressions for correlation functions are derived; they are shown to obey scaling; numerical transfer-integral values obtained for a discrete version of the model exhibit the same critical behavior. Furthermore, it is shown in detail that the onset of the transition can be characterized by an entropic stabilization of an—otherwise unstable—nonlinear field configuration, a soliton-like domain wall (DW) with macroscopic energy content. The statistical mechanics of the DW provides an exact estimate of the critical temperature for a wide range of the discretization parameter; this suggests that the transition can be accurately viewed as being driven by a nonlinear entity. |
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Keywords: | statistical mechanics solitons correlations scaling transfer integral |
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