Inversion Tunneling in Symmetric and Asymmetric Double-Well

We revise the conventional two-state theory for inversion tunneling of the ammonia molecule. A Gaussian wave packet peaked at the equilibrium position and with a negligible part in the barrier region is used to model the initial nitrogen atom. The inversion period of the nitrogen atom agrees with the real one. Compared to the two-state results, the time behavior of the probability in wells has additional small oscillation in a short time scale. For the asymmetric double-well, tunneling from the higher well to the lower well occurs generally. Through the help of a kick initial momentum, tunneling from the lower well to the high well is possible. But the time behavior in wells becomes irregular.