An approximate density-functional method using the Harris-Foulkes functional.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Dynamics

Background:

• Molecular Kohn-Sham calculations provide accurate electronic structure but are computationally expensive for large systems or long trajectories.
• Evaluating energies at multiple geometries is crucial for understanding molecular behavior and reaction pathways.

Purpose of the Study:

• To develop an efficient method for approximating molecular energies at diverse geometries.
• To leverage reference Kohn-Sham calculations to reduce computational cost in molecular simulations.

Main Methods:

• A novel approach using decomposed Kohn-Sham electron density from a reference geometry.
• Atomic fragments of the reference density are repositioned to approximate density at new geometries.
• Energy evaluation using the Harris-Foulkes functional.

Main Results:

• Preliminary results on a biological quantum-mechanics/molecular-mechanics trajectory are promising.
• Errors using the reference-geometry Harris-Foulkes method are comparable to the difference between PBE and BLYP functionals.
• The method demonstrates potential for significant computational savings.

Conclusions:

• The proposed method offers an efficient way to approximate molecular energies, reducing the need for full self-consistent calculations at every step.
• This technique is particularly valuable for large-scale simulations like biological trajectories.
• Further validation across various systems and functionals is warranted.