Moving nonlinear localized vibrational modes for a one-dimensional homogenous lattice with quartic anharmonicity

Moving nonlinear localized vibrational modes (i.e. discrete breathers) fur the one-dimensional homogenous lattice with quartic anharmonicity are obtai ned analytically by means of a semidiscrete approximation plus an integrati on. In addition to the pulse-envelope type of moving modes which have been found previously both analytically and numerically, we find that a kink-env elope type of moving mode which has not been reported before can also exist for such a lattice system. The two types of modes in both right- and left- moving form can occur with different carrier wavevectors asd frequencies in separate parts of the omega(q) plane. Numerical simulations are performed and their results are in good agreement with the analytical predictions.