Diffraction pattern degradation driven by intense ultrafast X-ray pulse for [formula omitted].

• X-ray pulse intensity influence on hydrogen ion degradation is considered. • Trajectory method is applied to study object degradation. • Results for different hydrogen ion internuclear distances. are compared The drastic evolution of molecular systems exposed to ultrashort intense X-ray pulse is a fundamental obstacle for single-particle imaging (SPI) by means of X-ray free electron lasers (XFEL). Here we tackle the simplest molecule H 2 + and its diffraction pattern degradations in the strong ultrashort X-ray beam. The semiclassical method of the problem solution and its advantages are described in detail. We apply the method to calculate the electron density autocorrelation functions (ACF) for a few internuclear distances and then discuss numeric simulation data. [ABSTRACT FROM AUTHOR]