$RDF group                     (relevant for RUNTYP=MD)                         
                                                                                
  This group defines the pairs of atoms for which the                           
radial distribution functions are to be computed, at the                        
end of a molecular dynamics trajectory.  The input is                           
similar in style to $EFRAG, consisting of separate lines,                       
with the word STOP ending each particular pair.                                 
                                                                                
Line 1.   NRDF=                                                        
gives the number of RDFs which should be computed.                              
                                                                                
Line 2.                                     
gives a string for the printout (a good choice involves                         
both atoms, such as ClCl), the name of the $FRAGNAME                            
containing the first atom of the pair, the name of the                          
$FRAGNAME input group with the second atom of the pair, and                     
how many such pairs exist.                                                      
                                                                                
Line 3.                                            
gives a label (arbitrary), the position of the atom within                      
the $FRAG1 group, and the 2nd atom's within the $FRAG2.                         
This line must be repeated  times.                                    
                                                                                
Line 4.    STOP                                                                 
the word STOP ends this RDF's pair input.                                       
                                                                                
Lines 2-4 must then be repeated a total of  times.                     
                                                                                
An example will make this all clear.  If there is only one                      
type of fragment used, such as water (so $EFRAG contains                        
only FRAGNAME=WATER), and assuming that this $WATER group                       
defining the water EFP has atoms in the order O,H,H:                            
                                                                                
$RDF                                                                            
nrdf=3                                                                          
OO       water   water    1                                                     
  dum   1   1                                                                   
STOP                                                                            
OH       water   water    4                                                     
  dum   1   2                                                                   
  dum   1   3                                                                   
  dum   2   1                                                                   
  dum   3   1                                                                   
STOP                                                                            
HH       water   water    4                                                     
  dum   2   2                                                                   
  dum   2   3                                                                   
  dum   3   2                                                                   
  dum   3   3                                                                   
STOP                                                                            
 $end                                                                           
                                                                                
==========================================================                      
                                                                                
                                                                                
                                                                                
                                                                                
==========================================================                      

generated on 7/7/2017