Sent to CCL by: "Ly Minh Nguyen" [nguyenminhly2209-$-yahoo.com] Dear sir, I'm Ly, Viet Nam I have a problem with SN1 reaction. I want to optimize transition state of SN1 subtitution reaction ( 2 structure ) but I don't know how to do this. Can I use QST2 and QST3 key word for optimizing ? Please help me. Thanks