Modular implementation of the linear and cubic-scaling orbital minimization methods in electronic structure codes using atomic orbitals

TL;DR

This paper introduces a modular, parallel implementation of orbital minimization methods in electronic structure calculations, demonstrating improved performance for large insulating systems using atomic orbitals.

Contribution

It presents a modular approach integrating external libraries for efficient, parallel cubic and linear-scaling solvers within electronic structure codes.

Findings

Linear-scaling solvers outperform cubic-scaling ones for large systems.

Parallel performance is demonstrated for systems with hundreds of atoms.

Modular implementation enhances flexibility and efficiency in electronic structure calculations.

Abstract

We present a code modularization approach to design efficient and massively parallel cubic and linear-scaling solvers for electronic structure calculations using atomic orbitals. The modular implementation of the orbital minimization method, in which linear algebra and parallelization issues are handled via external libraries, is demonstrated in the SIESTA code. The DBCSR and ScaLAPACK libraries are used for algebraic operations with sparse and dense matrices, respectively. The MatrixSwitch and libOMM libraries, recently developed within the Electronic Structure Library, facilitate switching between different matrix formats and implement the energy minimization. We show results comparing the performance of several cubic-scaling algorithms, and also demonstrate the parallel performance of the linear-scaling solvers, and their supremacy over the cubic-scaling solvers for insulating systems with sizes of several hundreds of atoms.