Monte Carlo determination of the oscillator strength and excited state lifetime for the Li 2²S → 2²P transition

A recently developed Monte Carlo method is used to compute the 2 2 S → 2 2 P transition dipole moment of Li. This approach employs a guided Metropolis random walk with quantum Monte Carlo “side” walks to sample the required probability distributions. The transition dipole moment is employed to obtain the oscillator strength and excited‐state lifetime. Our most accurately converged calculations yield an oscillator strength of 0.742(7) and excited‐state lifetime of 27.41(35) ns. These results are in excellent agreement with precise experimental measurements of 0.742(1) and 27.29(4) ns, respectively. In addition, single‐state expectation values are computed for both states. Monte Carlo parameters, such as the time step size and the convergence time, are varied in order to study their effect on computed results.