Simulations of 2:1 MMR capture and stability in q − τ_m/τ_e parameter space. The mass of the inner planet m_i = 10 M_⊕. Green: stable resonance capture. Yellow: overstable resonant capture. Purple: resonance escape after temporary capture. The solid lines are the criteria derived in this study, whereas the dashed lines represent the stability and escape criteria of Deck & Batygin (2015) (their Eqs. 15 and 21). The solid and dotted blue lines represent our second-order (Eq. B16) and first-order (Eq. B17) AMD criteria, respectively.