Exploiting temporal nonlocality to remove scaling bottlenecks in nonadiabatic quantum dynamics


An extension of the full multiple spawning (FMS) method for quantum non-adiabatic dynamics that capitalizes on the global nature of quantum mechanics and on the deterministic nature of the FMS method is discussed. The FMS method uses a classically motivated time-dependent basis set for the wave function and here we demonstrate that the choice of a temporally nonlocal basis set can reduce the scaling of the dominant effort in ab initio multiple spawning from O(N2) to O(N), where N is the number of basis functions describing the nuclear degrees of freedom. The procedure is applied to a two-dimensional two electronic state model problem and we show that the temporally nonlocal basis set provides accurate expectation values and branching ratios over a broad range of energies.

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