Soliton and Soliton-Pair as the Intrinsic Phonon Localized Modes in an Anharmonic Monoatomic Chain

With the use of coherent-state method, a quantum approach for the intrinsic phonon localized modes in an anharmonic monoatomic chain is given. It is shown that the envelope soliton with zerogroup velocity can exist in the lattice and that the frequency of carrier wave is above the top of the frequency band. A new type of the intrinsic phonon localized mode which we call the soliton-pair intrinsic localized mode in the chain is also reported.