[gmx-users] Problems with OPLS topology files

[Mark Abraham]

Goran Krilov wrote:
> Thanks!
> I am enclosing the piece of the topology file (2607 is the first line 
> after the
> [dihedrals] heading:
> 
>  342    97    98   105     3      0.62760   1.88280   0.00000  -2.51040 
>  0.0000  0.0000
>   342    97   323   324     3      0.00000   0.00000   0.00000   0.00000 
>  0.0000  0.0000
>   342    97   323   327     3      0.00000   0.00000   0.00000   0.00000 
>  0.0000  0.0000
> 
> [ dihedrals ]                                                           
>         
> ;  ai    aj    ak    al   funct    c0         c1        c2        c3     
>   c4      c5   
>     2     5     1    25     1      8.36800   0.00000  -8.36800   0.00000 
>  0.0000  0.0000

Look at Table 5.4... dihedral function type 1 doesn't take 6 parameters. 
  Because it is actually expecting 3, gromacs infers that because 6 = 
2*3 that you're trying to do a free-energy perturbation calculation. 
This explains the error message.

Mark