A theory of intrinsic localized modes (ILMs) in anharmonic lattices is
developed, which allows one to reduce the original nonlinear problem to a
linear problem of small variations of the mode. This enables us to apply the
Lifshitz method of the perturbed phonon dynamics for the calculations of ILMs.
In order to check the theory, the ILMs in monatomic chain are considered. A
comparison of the results with the corresponding molecular dynamics
calculations shows an excellent agreement.Comment: 9 pages, 1 figure, 1 tabl