koopmans: An Open-Source Package for Accurately and Efficiently Predicting Spectral Properties with Koopmans Functionals
Over the past decade we have developed Koopmans functionals, a computationally efficient approach for predicting spectral properties with an orbital-density-dependent functional framework. These functionals impose a generalized piecewise linearity condition to the entire electronic manifold, ensuring that orbital energies match the corresponding electron removal/addition energy differences (in contrast to semilocal DFT, where a mismatch between the two lies at the heart of the band gap problem and, more generally, the unreliability of Kohn-Sham orbital energies). This strategy has proven to be very powerful, yielding molecular orbital energies and solid-state band structures with comparable accuracy to many-body perturbation theory but at greatly reduced computational cost while preserving a functional formulation. This paper reviews the theory of Koopmans functionals, discusses the algorithms necessary for their implementation, and introduces koopmans, an open-source package that contains all of the code and workflows needed to perform Koopmans functional calculations and obtain reliable spectral properties of molecules and materials.
WOS:001114702100001
2023-08-23
REVIEWED
Funder | Grant Number |
Division of Materials Research | 179138 |
Swiss National Science Foundation | 205602 |
NCCR MARVEL, a National Centre of Competence in Research - Swiss National Science Foundation | HORIZON-EUROHPC-JU-2021-COE-01 |
MaXyMAterials design at the eXascaleya European Centre of Excellence - European Union's program | 103.02-2021.95 |
Vietnam National Foundation for Science and Technology Development (NAFOSTED) | DMR-1654625 |
Division of Materials Research of the National Science Foundation | |