Hirshfeld atom refinement based on projector augmented wave densities with periodic boundary conditions

Area of Science:

• Crystallography
• Solid-state chemistry
• Computational chemistry

Background:

• Hirshfeld atom refinement (HAR) is a key X-ray diffraction technique.
• HAR accurately determines hydrogen atom positions, comparable to neutron diffraction.

Purpose of the Study:

• To evaluate a novel approach for HAR using projector augmented wave (PAW) densities.
• To assess the impact of three-dimensional periodic boundary conditions on HAR accuracy.

Main Methods:

• Utilized PAW densities with 3D periodic boundary conditions for HAR.
• Compared results against methods neglecting crystal environment and non-periodic quantum mechanical approximations.
• Evaluated various density functionals, including SCAN and revSCAN.

Main Results:

• The PAW-based periodic approach demonstrated improved HAR accuracy.
• Performance was comparable to non-periodic quantum mechanical methods for solid-state environments.
• SCAN and revSCAN functionals proved most effective for these calculations.

Conclusions:

• Periodic PAW densities offer a viable and effective method for HAR.
• This approach enhances the treatment of the crystal environment in diffraction studies.
• SCAN and revSCAN functionals are recommended for future periodic HAR calculations.