I am trying to generate the full S-curve for a steady perfectly stirred reactor (PSR). It is easy to generate the upper branch (strong flame until extinction) and the lower branch (until ignition) of S-curve in Chemkin Pro. But I couldn't generate the middle branch (unstable flame) of the curve in Chemkin. Whenever I try to get a point on the middle branch, it always reaches a steady state condition corresponding to either the upper or the lower branch. Can anyone help me about how I can generate the data for middle branch? Is it possible to use arc length continuation method in case of PSR in Chemkin Pro?