LAUSR

Dysprosium(III) ions are promising candidates for the design of single‐ion magnets (SIMs) as they show an intrinsic strong magnetic anisotropy. However, time‐demanding multireference methods are usually necessary to reproduce low‐lying magnetic states. In this work, we present an improved wave function‐based semiempirical ligand‐field (LF) theory approach to obtain magnetochemical properties of dysprosium(III)‐based SIMs. We reduce the computational effort by replacing the central dysprosium(III) ion with either yttrium(III) or lutetium(III), which allows to obtain a closed‐shell wave function from Hartree–Fock calculations. The wave function is subsequently used to determine a so‐called diamagnetic–electrostatic pseudo‐potential (DEPP) of the compound, which in turn can be applied to LF theory to obtain magnetochemical properties. The presented approach is tested against ab initio CASSCF/RASSI‐SO reference calculations and shows accurate prediction of magnetic anisotropy axes and a significant accuracy improvement as compared to point charge‐based LFT methods. In addition, we also introduce an improved electrostatic (IES) approach, which applies the obtained DEPPs to a known electrostatic method introduced by Chilton et al. (Nat. Commun. 2013, 4, 2551) to obtain the direction of the main anisotropy axis in dysprosium(III)‐based SIMs. © 2018 Wiley Periodicals, Inc.