Mixed Quantum-Classical Simulations. In this work, we use a variety of MQC dynamics methods to investigate the resonance behavior of VSC. In particular, we use Eq. 4 as the Hamiltonian and only include the key vibrational states in Eq. 7 as our quantum subsystem and all the other DOFs as the classical DOFs. This means that in the vibration subspace |i⟩ ∈ {|ν L ⟩, |ν ′ L ⟩, |ν ′ R ⟩, |ν R ⟩} (which are the diabatic states), we use projection operator P = i |i⟩⟨i| to represent the model potential V ( R0 ) in Eq. 4 as follows