Ab Initio Calculation of Total X-ray Scattering from Molecules

Area of Science:

• Computational chemistry
• Quantum mechanics
• Atomic and molecular physics

Background:

• Accurate calculation of X-ray scattering cross sections is crucial for understanding material properties.
• Existing methods may lack efficiency or accuracy, particularly for complex systems.

Purpose of the Study:

• To present a novel, efficient, and accurate method for calculating total X-ray scattering cross sections.
• To investigate the dependence of inelastic X-ray scattering on molecular geometry.

Main Methods:

• Direct calculation of total X-ray scattering cross sections from ab initio electronic wave functions.
• Utilizing analytical integrals of Gaussian-type functions over the scattering operator.
• Employing multiconfigurational wave functions for enhanced accuracy.

Main Results:

• The method provides accurate total X-ray scattering cross sections for molecules like H2 and CO2.
• A strong dependence of the inelastic scattering component on molecular geometry was identified.
• Validation against experimental data and previous theoretical calculations confirmed the method's reliability.

Conclusions:

• The developed method offers a computationally efficient and accurate approach for X-ray scattering calculations.
• The findings highlight the significant impact of molecular geometry on inelastic X-ray scattering.
• This method is suitable for integration with quantum molecular dynamics and analysis of ultrafast X-ray scattering experiments.