The absorption spectrum of a potassium atom in a Xe cluster

We calculate the absorption spectrum for a simple model that mimics a potassium atom in a Xe cluster. The time evolution of the electron wave function is calculated by a fast Fourier transform method while the nuclear motion is treated classically. The initial nuclear configurations are generated by a Monte Carlo method. We examine which features in the spectrum are caused by electron, potassium ion or Xe motion and the frequency resolution at which these features appear.