Efficient DFT Solver for Nanoscale Simulations and Beyond.

Area of Science:

• Computational materials science
• Quantum chemistry
• Condensed matter physics

Background:

• Density Functional Theory (DFT) is crucial for materials simulation.
• Current DFT methods face limitations in system size and computational cost.
• Orbital-free DFT (OF-DFT) aims to overcome these limitations but requires accurate solvers.

Purpose of the Study:

• Introduce a novel orbital-free DFT solver, OE-SCF.
• Extend the applicability of DFT to beyond nanoscale system sizes.
• Retain predictive accuracy for large-scale simulations.

Main Methods:

• Developed the one-orbital ensemble self-consistent field (OE-SCF) method.
• Treated the Pauli potential as an external potential, updated iteratively.
• Performed large *ab initio* simulations using OE-SCF on a single CPU.

Main Results:

• OE-SCF demonstrated rapid convergence, outperforming existing solvers.
• Enabled the largest *ab initio* simulations of silicon nanoparticles (up to 16 nm).
• Calculated polarization and interface charge transfer in metal-silicon-metal systems.

Conclusions:

• OE-SCF significantly advances the capabilities of OF-DFT.
• Facilitates accurate simulations of large, industrially relevant material systems.
• Paves the way for integrating more accurate functionals into OF-DFT.