Dear all,
I know that I can add an external force to one set of atoms by scripting in material studio 7.0, just as below:

#!perl

use strict;
use Getopt::Long;
use MaterialsScript qw(:all);

my \\\$doc = \\\$Documents{"SWNT.xsd"};
my \\\$forcite = Modules->Forcite;
my \\\$dynamics = \\\$forcite->Dynamics;

    



Modules->Forcite->ChangeSettings([Ensemble3D => "NVT",
                                  NumberOfSteps => 50000,
                               CurrentForcefield => "Dreiding",
                               WriteForces=> "Yes",
    Quality => "Coarse", 
    
    TimeStep => 1, # fs
    TrajectoryFrequency => 20,
    ExternalForceSet => "Right",  
        ExternalForceStrength => 10000, 
        ExternalForceX=>0,
        ExternalForceY=>0,
        ExternalForceZ=>-1,
        CounterExternalForce =>"No",
        
        
  ]);


Modules->Forcite->Dynamics->Run(\\\$doc);


But how to add external force in material studio 6.1?
Thanks. 
Best regards,
Yours 
CHENG Xu