Delocalization error poisons the density-functional many-body expansion.

ABSTRACT: The many-body expansion is a fragment-based approach to large-scale quantum chemistry that partitions a single monolithic calculation into manageable subsystems. This technique is increasingly being used as a basis for fitting classical force fields to electronic structure data, especially for water and aqueous ions, and for machine learning. Here, we show that the many-body expansion based on semilocal density functional theory affords wild oscillations and runaway error accumulation for ion-water interactions, typified by F^-(H₂O) _N with N ≳ 15. We attribute these oscillations to self-interaction error in the density-functional approximation. The effect is minor or negligible in small water clusters, explaining why it has not been noticed pre

SUBMITTER: Broderick DR 

PROVIDER: S-EPMC11575576 | biostudies-literature | 2024 Dec

REPOSITORIES: biostudies-literature