Within the Eigenvector Following routine [7], the option exists to optimize a transition state. To do this, use TS. Preliminary indications are that the TS method is much faster and more reliable than either SIGMA or NLLSQ. TS appears to work well with Cartesian coordinates. In the event that TS does not converge on a stationary point, try adding RECALC=5 to the keyword line.
Caution: When a transition state is optimized, and some optimization flags are not set for optimization, the optimized structure might have a significant gradient. This usually happens when the fixed atoms are not in their optimized positions.