Short-range DFT correlation within the RAS-SF method

The restricted active space spin-flip (RAS-SF) approach is a multistate, spin-complete, variational and size consistent method applicable to systems featuring electronic (near-)degeneracies. In contrast to CASSCF it does not involve orbital optimizations and so avoids issues such as root-flipping and state averaging. The main deficiency of the RAS-SF family of methods is the lack of effective dynamic correlation in the case of small to moderate active spaces. On the other hand, density functional theory (DFT) in many cases provides a satisfactory description of the short-range dynamic correlation.

The objectives of this project are: (i) recover the lack of dynamic correlation by merging the RAS-SF wave function with short-range DFT correlation, (ii) explore the properties of this hybrid model and (iii) apply it to the study of singlet fission and/or triplet-triplet annihilation processes.

The candidate should have a basic knowledge on quantum mechanics (assumed in chemistry and physics BSc. students), and preferably have experience in the computation of the electronic structure of molecular systems with multiconfigurational wave function approaches.