TITLE: Influence of third order dispersion on the bound state of two solitons of
             the NLS equation

           Department of Theoretical Physics
           National Institute for Physics and Nuclear Engineering
           P.O.Box MG-6, Magurele, Bucharest, Romania

 e-mail:      avisin@theor1.theory.nipne.ro
 
                  dgrecu@theor1.theory.nipne.ro

ABSTRACT:

Using Karpman-Soloviev perturbation procedure the influence of the
third order dispersion on the bound state of two solitons of the NLS
equation is investigated. The problem has two small parameters
(supposed to be of the same order): the small overlap of the two well
separated solitons, and the amplitude of the third order dispersion. If
the velocities of the two solitons are the same, a bound state is
formed, with an oscillating expression for the distance between
solitons. When the third order dispersion is introduced a slow
monotonous increasing function of time is superposed over this
oscillatory behaviour.