Photoabsorption spectra in the continuum of molecules and atomic clusters

We present linear response theories in the continuum capable of describing photoionization spectra and dynamic polarizabilities of finite systems with no spatial symmetry. Our formulations are based on the time-dependent loca l density approximation with uniform grid representation in the three-dimen sional Cartesian coordinate. Effects of the continuum are taken into accoun t either with a Green's function method or with a complex absorbing potenti al in a real-time method. The two methods are applied to a negatively charg ed cluster in the spherical jellium model and to some small molecules (sila ne, acetylene and ethylene). (C) 2001 American Institute of Physics.