In all cases, the initial excited state's population returned to the ground state, featuring an exponential decay profile. Figure shows the excited state's population decay curves for DC-FSSH, CSS-AIMS, and a few selected MCTDH and its ML-variant simulations. The population curves are fitted with both single and double exponential functions to extract the time constants associated with the decay processes. A mono-exponential function of the form, 𝑓 𝑚 (𝑡) = 𝑁 0 + (1 -𝑁 0 )𝑒 -𝑡/𝜏 is used,