Excited-state molecular dynamics simulation based on variational quantum algorithms

We propose an excited-state molecular dynamics simulation method based on variational quantum algorithms at a computational cost comparable to that of ground-state simulations. We utilize the feature that excited states can be obtained as metastable states in the restricted variational quantum eigensolver calculation with a hardware-efficient ansatz. To demonstrate the effectiveness of the method, molecular dynamics simulations are performed for the S1 excited states of H2 and CH2NH molecules. The results are consistent with those of the exact adiabatic simulations in the S1 states, except for the CH2NH system, after crossing the conical intersection, where the proposed method causes a nonadiabatic transition.