Combining Real-Space and Local Range Separation – The MH24 Locally Range-Separated Local Hybrid Functional

In this work, the development of a new general-purpose exchange-correlation hybrid functional based on the recent locally range-separated local hybrid (LRSLH) approach is presented. In particular, the new functional, denoted as MH24, combines a non-empirical treatment of the admixture of locally range-separated long-range exact exchange with a new real-space separation approach for the real-space exact-exchange admixture governed by the local mixing function (LMF) and a new empirical LYP-based approach for the correlation functional to enable a flexible description of same- and opposite-spin correlation effects. The nine empirical parameters of the MH24 model have been optimized using a state-of-the-art super-self-consistent-field approach, which exploits the sensitivity of specific properties such as core ionization potentials, electron affinities and atomization energies to the exact-exchange admixture in specific regions in real space and the separation of the LMF into a core, valence and asymptotic part. The optimized MH24 functionals are shown to be able to simultaneously provide good accuracy for valence and core properties as well as for electron affinities and noble gase dimer dissociation curves, while satisfying multiple known exact constraints related to the exact-exchange admixture in hybrid functionals. MH24 is thus a major step toward the development of more sophisticated hybrid functional models.