 Exponential-potential scalar-dominated power-law solution

For $V=V_0{e}^{-\lambda \phi /M_{\mathrm{Pl}}}$, $\lambda \ne 0$, the displayed ansatz satisfies the flat Friedmann equation and scalar field equation of motion when $V_0{t}_0^2=2M_{\mathrm{Pl}}^2(6-{\lambda }^2)/{\lambda }^4$. Its equation-of-state parameter is $w=-1+{\lambda }^2/3$ and its deceleration parameter is $q={\lambda }^2/2-1$. It gives exponential-potential power-law inflation only for $0<{\lambda }^2<2$; the same algebraic family includes decelerating expansion outside that range when its potential normalization is real.