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Phys. Rev. E 70, 056615 (2004) [6 pages]

Integrable generalization of the Toda law to the square lattice

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P. M. Santini*
Dipartimento di Fisica, Università di Roma “La Sapienza,” and Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Piazza le Aldo Moro 2, I-00185 Roma, Italy

M. Nieszporski
Katedra Metod Matematycznych Fizyki, Uniwersytet Warszawski, ulica Hoża 74, 00-682 Warszawa, Poland

A. Doliwa
Wydział Matematyki i Informatyki, Uniwersytet Warmińsko-Mazurski w Olsztynie, ulica Żołnierska 14 A, 10-561 Olsztyn, Poland

Received 9 July 2004; published 23 November 2004

We generalize the Toda lattice (or Toda chain) equation to the square lattice, i.e., we construct an integrable nonlinear equation for a scalar field taking values on the square lattice and depending on a continuous (time) variable, characterized by an exponential law of interaction in both discrete directions of the square lattice. We construct the Darboux-Bäcklund transformations for such lattice, and the corresponding formulas describing their superposition. We finally use these Darboux-Bäcklund transformations to generate examples of explicit solutions of exponential and rational type. The exponential solutions describe the evolution of one and two smooth two-dimensional shock waves on the square lattice.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevE.70.056615
DOI:
10.1103/PhysRevE.70.056615
PACS:
03.50.−z, 05.45.−a, 63.20.Pw, 05.50.+q

*Email address: paolo.santini@roma1.infn.it

FAX: +48 22 622 45 08. Email address: maciejun@fuw.edu.pl

Email address: doliwa@matman.uwm.edu.pl