Journal Article Research Support, Non-U.S. Gov't divide-and-conquer method linear scaling conical intersection degenerate phenomena dynamic polarizability electron-correlation theory excited state excited-state theory generalized Hartree-Fock graphical processor unit heavy element linear-scaling long-range correction relativistic quantum chemistry spin-dependent effect spin-flip spin-free effect tensor contraction engine time-dependent density functional theory time-dependent density functional tight-binding method time-dependent density-functional tight-binding method two-component relativistic framework