METHODS OF UNITARY-TRANSFORMS IN PROBLEMS CONCERNING ATOMS IN INTENSEELECTROMAGNETIC-FIELDS

This paper considers a method of unitary transforms, which makes it po ssible to describe the dynamics of a complex atom in a strong circular ly polarized laser field with the use of a stationary Hamiltonian whos e asymptotic behavior is independent of the held. This approach allows one to apply the Hartree-Fock variational procedure to derive a coupl ed set of equations for quasienergies and wave functions of an ''atom + field'' system. As an example, we consider the calculation of the dy namic polarizability for a complex atom in a high-frequency field. Spe cific features of the application of the method of unitary transforms to systems that require the quantum description of the field are illus trated for a problem of potential scattering of a charged particle in a quantized field.