Predictive Description of Condensed-Phase Hyperfine Coupling Constants Relies on Dielectric Screening of Long-Range Exchange

Abstract Hyperfine coupling constants (HFCCs) provide a direct probe of the interaction between electron and nuclear spins and are important descriptors in the design of molecular spin qubits for quantum information science. Accurate prediction of HFCCs in condensed-phase environments requires describing the influence of environmental polarization on the underlying spin density. Here, we demonstrate that dielectric screening of the exchange interaction in the long-range limit of range-separated hybrid (RSH) functionals, as introduced in SRSH, substantially improves calculated 1H and 13C HFCCs. Systematic analysis of arene radical anions examines the effects of dielectric screening, basis-set choice, and the weight of short-range exact exchange, demonstrating the improved accuracy achieved by using SRSH–PCM for calculating HFCCs. The applicability of SRSH–PCM is further demonstrated for semiquinone derivatives, where the screened treatment captures changes in the HFCCs across different dielectric environments. These results establish dielectric screening of long-range exchange as key for accurately predicting condensed-phase hyperfine interactions and their response to changes in the molecular environment, providing a basis for reliably extending such calculations to more complex EPR-active systems.