An Efficient DFT Solver for Nanoscale Simulations and Beyond

TL;DR

The paper introduces OE-SCF, an efficient orbital-free DFT solver that enables large-scale nanoscale simulations with high accuracy, outperforming existing methods and allowing for simulations of systems up to 16 nm in size.

Contribution

The paper presents OE-SCF, a novel iterative orbital-free DFT method that significantly reduces computational cost and extends applicability to larger nanoscale systems.

Findings

OE-SCF converges in about a dozen iterations.

Successfully simulated silicon nanoparticles up to 16 nm.

Enabled large-scale ab initio simulations on a single CPU.

Abstract

We present the One-orbital Ensemble Self-Consistent Field (OE-SCF) method, an {alternative} orbital-free DFT solver that extends the applicability of DFT to system sizes beyond the nanoscale while retaining the accuracy required to be predictive. OE-SCF is an iterative solver where the (typically computationally expensive) Pauli potential is treated as an external potential and updated after each iteration. Because only up to a dozen iterations are needed to reach convergence, OE-SCF dramatically outperforms current orbital-free DFT solvers. Employing merely a single CPU, we carried out the largest ab initio simulation for silicon-based materials to date. OE-SCF is able to converge the energy of bulk-cut Si nanoparticles as a function of their diameter up to 16 nm, for the first time reproducing known empirical results. We model polarization and interface charge transfer when a Si slab is sandwiched between two metal slabs where lattice matching mandates a very large slab size. Additionally, OE-SCF opens the door to adopt even more accurate functionals in orbital-free DFT simulations while still tackling systems sizes beyond the nanoscale.