Transition probability P₁(t) = |a₁(t)|² for (a) gt₀ = –5, (b)gt₀ = –1, (c) gt₀ = –0.5, and (d) gt₀ = 0 with f₁/g = 0. The parameters are given as g = 1, f0/g=23 , and ν₁/g = 6. The initial conditions are a₁(t₀) = 1 and a₂(t₀) = 0. The dashed lines are the exact results of the final transition probability P1f .