Peculiarity of electron density calculation during interaction of ultrashort laser pulse with nitrogenous base of DNA molecule adenine

Today, ultrashort laser pulses are used to study and analyze biomolecules. Their advantages over X-rays lie in the speed of measurement and accuracy, which allows studying the structure of a molecule on a time scale commensurate with the time of various biochemical processes in it. However, the practical possibility of studying chemical and biological processes in facilities using existing and promising X-ray free-electron lasers requires the development of a theory of the interaction of laser pulses with matter. In this article we will consider the interaction of an ultrashort laser pulse (USPs) with the base of the DNA (Deoxyribonucleic acid) molecule - adenine. In more
detail we will consider the calculation of the photon birth probability, after the interaction of the pulse with the molecule. We will build a model of the base of the molecule and propose a method for calculating the electron density for the case when the substance has a different elemental composition.