An example of the unphysical effects of ZPE leakage is seen in the dynamics of water dimers. A weak interaction binds the dimer in its lowest vibrational state. However, ZPE leaks from the fast OH vibrational modes to the slow intermolecular modes, leading to an artificial dimer dissociation within a few picoseconds during dynamics in the ground state. LP-ZPE inhibits this artifact by continuously monitoring the mean kinetic energy in each OH pair and correcting them when needed. 24 In our implementation of the fewest-switches surface hopping 32 (FSSH), the time-dependent electronic wave function Ansatz is written as 33