Abstract
The dynamics of the Fermi-Pasta-Ulam chain with quartic anharmonicity are numerically investigated by means of a stimulating force of Gaussian time shape, which acts on a single atom. Depending on the strength and duration of this force, several phenomena have been observed. A pulse of originally continuous envelope disintegrates into solitary objects (‘multifurcative process’), which may be ultrasonic solitons of kink type, or subsonic and self-localized solitons of oscillating nature. In the oscillations of the latter two, frequencies are involved, above the Debye frequency, and the spatial envelope displays a ‘breathing’ behaviour. Some analytical background is also presented.