Intrinsic Excitation Modes Compatible with Large-Amplitude Collective Motion in the TDHF Theory

Abstract

Within the framework of the time-dependent Hartree-Fock (TDHF) theory, a systematic microscopic method is proposed to properly describe intrinsic (particle-hole) excitation modes in the generalized moving frame, which is specified by variations of the time-dependent mean field associated with large-amplitude collective motion. It is demonstrated that the proper intrinsic Hamiltonian for specifying the intrinsic excitation modes cannot be identified by the time-displacement operator in the moviing frame, even though the operator plays a decisive role in specifying the single-particle orbits in the moving frame. It is also clarified that the intrinsic excitation modes are not always definable, depending on a degree of variations of their internal structure induced by the time-evolution of the large-amplitude collective motion. A condition to display the range of validity for the very concept of the intrinsic excitation modes is given. The stability condition of the generalized moving frame (i. e., the large-amplitude collective motion) is discussed in terms of the intrinsic excitation modes.