Microscopic optical potentials for time-dependent quantum systems

Abstract

The numerical solution of the time-dependent Schrödinger equation often relies on the expansion of the wavefunction in terms of a truncated set of orbitals spanning a finite model space. The projection of the Schrödinger equation onto a finite subspace of the Hilbert space necessarily leads to an effective interaction described by a complex operator. The imaginary part of this optical potential accounts globally for the coupling between the model space and its explicitly neglected complement. We discuss a nonperturbative approximation to this optical potential and give some details for the numerical evaluation of the matrix elements involved.