Influence of repulsive and attractive potentials on the energy localization in 1D morse lattice with an impurity

Molecular dynamics simulations have been carried out to investigate the ene rgy localization in a one-dimensional Morse lattice with an impurity. The e nergy distribution around the impurity site is studied. It shows that the p otential energy localization is only limited to the impurity and its neares t neighboring particles. Influence of the repulsive and attractive parts of the potential on the energy localization around an impurity has also been studied. The results show that at intermediate and high temperatures the re pulsive potential dominates the quantitative behavior of the energy localiz ation of the impurity. The attractions are manifested primarily in the low temperature range, but this effect decreases as the temperature increases a nd is almost negligible at high temperatures. They also show that in therma l equilibrium, the average potential energy of the impurity increases with decreasing repulsion stiffness; and decreases with reduced attraction one. The results are explained by the soliton fusion theory of a Toda lattice.