A Variational Approach to London Dispersion Interactions without Density Distortion

Area of Science:

• Quantum Chemistry
• Computational Physics
• Atomic and Molecular Interactions

Background:

• Accurately calculating long-range interactions is crucial for understanding molecular behavior.
• Existing methods may struggle with precision for neutral systems.

Purpose of the Study:

• Introduce a novel variational wave function class for neutral systems.
• Develop a theoretical framework for calculating dispersion coefficients.
• Assess the impact of density distortion on London dispersion interactions.

Main Methods:

• Developed a class of variational wave functions.
• Optimized energy to derive explicit expressions for dispersion coefficients.
• Kept individual monomer densities fixed to isolate effects.

Main Results:

• Obtained explicit expressions for dispersion coefficients using ground-state pair densities.
• Achieved virtually exact dispersion coefficients for two hydrogen atoms up to C10.
• Demonstrated relative errors below 0.2% in other simple systems.

Conclusions:

• The new theoretical framework provides a clean approach for new approximations.
• The method accurately captures long-range interactions without altering monomer density matrices.
• This work enables precise assessment of density distortion effects on dispersion.