DFT version of MRSF-TDDFT (UMRSF-TDDFT; UMRSF for brevity) shall be presented here. As discussed in the Introduction, a new mixed reference has been introduced whose density (ρ MR 0 ) is the equiensemble density of the M S = +1 and M S = -1 components of a triplet state as shown in Eq. 1. Two open-shell molecular orbitals of the new mixed reference are defined by novel + andspin functions.