***, HCN <---> NHC Isomerization Reaction Path
 memory,1,m
 basis=3-21G

 l1=1.18282 ang      ! Starting geometry is transition state
 l2=1.40745 ang      
 a1=55.05 degree

 geometry={x;           ! Cs Symmetry
           C
           N,1,l1
           H,2,l2,1,a1}

 int
 rhf
 optg                   ! Enter geometry optimization
 method,qsdpath         ! Reaction path following
 option,idir=1          ! First step is along the transition vector
 print,history          ! Print optimization history