Example: IRC for HCN
********************

"Download IRC_HCN.run"

   #!/bin/sh

   # == IRC scan of the reaction path ==


   # The IRC calculation is split in two steps to illustrate the Restart feature.

   # In the first calculation only a few points are computed along the so-called 
   # 'forward' path. The definition of which is 'forward' and which is
   # 'backward' depends on the sign of the largest component of the normal mode
   # corresponding to the reaction coordinate. 

   # The RKF file from this partial IRC scan serves as restart file
   # for the next calculations that will continue the IRC scan.

   # The 'MaxPoints' key in the IRC block is used to limit the number of IRC 
   # points to compute.


   AMS_JOBNAME=irc1 $AMSBIN/ams << eor

   Task IRC
   System
       Atoms
           C       0.000000000000       0.000000000000       0.000000000000    
           N       0.000000000000       0.000000000000      -1.182644220000    
           H      -1.103250760411       0.000000000000      -0.322462130000    
       End
   End

   IRC
       MaxPoints 5
       Direction Forward
       CoordinateType Cartesian
       InitialHessian
           Type Calculate
       End
   End

   Engine DFTB
       Model DFTB3
       ResourcesDir DFTB.org/3ob-3-1
   EndEngine

   eor

   # In the second IRC run, the IRC scan is finished. We start with the RKF file
   # from the previous run and omit the MaxPoints from the settings, which means 
   # that the default 100 will be used. Note that the 100 also includes any points 
   # computed in the previous calculation. The program starts on
   # the forward path, continuing where the first calculation had stopped,
   # and completes it. Since we set the Direction to Both
   # then AMS proceeds to the backward path. After both paths are finished a summary 
   # of the path characteristics is printed at the end of the output file.


   AMS_JOBNAME=irc2 $AMSBIN/ams << eor

   Task IRC
   System
       Atoms
           C       0.000000000000       0.000000000000       0.000000000000    
           N       0.000000000000       0.000000000000      -1.182644220000    
           H      -1.103250760411       0.000000000000      -0.322462130000    
       End
   End

   IRC
       Restart
           File irc1.results/ams.rkf
       End
       ! Change options from the ones found in the restart file 
       ! (MaxIRCPoints and MaxPoints will be reset to defaults automatically)
       Direction Both
   End

   Engine DFTB
       Model DFTB3
       ResourcesDir DFTB.org/3ob-3-1
   EndEngine

   eor

