Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) as a Method of Choice for Nonadiabatic Molecular Dynamics
Seunghoon Lee, Woojin Park, Hiroya Nakata, Michael Filatov, Cheol Ho Choi
Abstract
The recently developed MRSF-TDDFT method is capable of alleviating the major limitations of the DFT, standard linear-response TDDFT as well as the original SF-TDDFT methods, thus providing a promising protocol for computing a wide range of molecular systems, from weakly correlated to strongly correlated. In this chapter, the main aspects of the new methodology are documented and the advantages of using it are highlighted. The authors have shown a way of expanding the response space by combining more than one reference state into a single mixed reference. Because LR-TDDFT based on the TD-KS equation is derived from a single Slater determinant, this type of mixed-reference approach has never been considered because of violation of the idem potency condition. When describing non-adiabatic transitions between adiabatic electronic states, e.g., in NAMD simulations, the probability of the transition depends critically on the first-order non-adiabatic coupling matrix element (NACME) defined.