Аннотация:In this contribution, we discuss a model based on the replacement of the potential describing the interaction of a single active electron with the nucleus or the nuclei of atoms or molecules, with a potential, separable in momentum space and consisting of several terms. Each term supports only one single electron bound state of the system. We apply this model to the description of the interaction of atomic and molecular hydrogen, hydrogen anion and water molecule with an external ultrashort laser pulse. As expected, this short range separable potential model works very well for the hydrogen negative ion due to the short range nature of it real potential. In the case of other systems, we show that, at high frequency, taking into account the