Molecular-dynamics simulation of effects of relaxation of polarization on atomic line shapes

The time-dependent difference-potential matrix generated by molecular-dynamics simulation in a system of one sodium atom in a bath of 255 argon atoms is used in a classical-path coupled states formalism to generate a resonance atomic line shape which incorporates the effects of relaxation of polarization. A comparable technique is used to generate the one-perturber spectrum, which is then used in the unified theories of Jablonski, Anderson, and Baranger, of Fano, and of Szudy and Baylis to predict the density-dependent line shape. At the high density used (2×${10}^{21}$ ${\mathrm{cm}}^{\mathrm{-}3}$), the Jablonski-Anderson-Baranger line shape is in excellent agreement with the simulated line shape, but the other unified theories show significant discrepancies. The effects of relaxation of polarization (‘‘m-changing effects’’ in quantum theory) on the line shape were found to be small.