High order forces and nonlocal operators in a Kohn-Sham Hamiltonian

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Real space pseudopotentials offer advantages in electronic structure calculations, including ease of implementation and flexibility.
• A key limitation is the slow convergence of interatomic forces compared to total energies, necessitating fine grids and increased computational cost.
• Existing methods require significant computational resources (memory, matrix-vector multiplications) for accurate force calculations.

Purpose of the Study:

• To develop a method that expedites the computation of interatomic forces in real space electronic structure calculations.
• To overcome the slow convergence issue of interatomic forces in real space methods.
• To enable accurate calculations of material properties without relying on excessively fine grids.

Main Methods:

• Implementation of a high-order integration technique for computing interatomic forces.
• Application of the developed method to real space electronic structure calculations.
• Validation of the technique through calculations on molecules and nanocrystals.

Main Results:

• The high-order integration technique significantly expedites the computation of interatomic forces.
• Accurate bond lengths and vibrational frequencies were obtained for molecules and nanocrystals.
• The method successfully avoids the need for fine real space grids, reducing computational demands.

Conclusions:

• The proposed method offers an efficient approach to calculating interatomic forces in real space electronic structure studies.
• This technique enhances the practicality of real space methods by mitigating computational bottlenecks.
• The findings pave the way for more accessible and efficient electronic structure investigations of materials.