Quasienergy pseudopotential method in the theory of interaction of a coherent electromagnetic field with matter

We formulate the quasienergy pseudopotential methods, allowing us to study the behavior of the electronic structure of a material in a coherent electromagnetic field. We show that after canonical transformation, we can look for the solution to the nonsteady-state Schrödinger equation in a basis of wave functions from extended Hubert space, substituting the quasienergy pseudopotential for the true nonsteady-state electronic potential. We prove that the familiar compensation theorem remains valid even in this case.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 33–37, February, 1992.