Comparison of Hartree-Fock and local density exchange appr oximations for calculation of radiation damage dynamics of light and heavy atoms in the field of x-ray free electron laser

Simulations of radiation damage in single molecule imaging using X-ray free electron laser use atomic rates calculated in the lowest order. We investigate the difference in ion yield predictions using Hartree-Fock and local density approximation for lig ht and heavy elements of biological sig- nificance. The results show that for short and bright pulses b oth approximations give very similar results for light atoms. For heavy atoms and for light atoms w ith smaller peak intensity the predic- tions may differ considerably. This presented analysis allo ws one to predict if the two approaches will produce similar results for a given atom in a pulse with c ertain parameters. We also discuss the choice of effective potential and gauge for the calculati on of transition rates.