[gmx-users] angle restraints in gromacs 4

[Brian Novak]

I am getting a warning from grompp about an angle restraint I have 
specified:

WARNING 1 [file test1.top, line 18]
      Duplicate atom index (1211) in angle_restraints

I specified the angle the same way as in gromacs 3.3, and I have seen no 
documentation suggesting that angle restraints are specified differently 
in version 4.

[ angle_restraints ]
; i j k l            type    theta0     fc             mult
651 1211 1683 1211     1      67.0     1500            1

Is this a harmless warning or do I need to specify the angle differently?

Thanks,
Brian


The contents of test1.top are:

; Include forcefield parameters
#include "ffG43a1.itp"

; Include chain topologies
#include "protein.itp"

[ angle_restraints ]
; i j k l            type    theta0     fc             mult
651 1211 1683 1211     1      67.0     1500            1

#include "extra_nacl.itp"

; Include water topology
#include "spc.itp"

#ifdef POSRES_WATER
; Position restraint for each water oxygen
[ position_restraints ]
;  i funct       fcx        fcy        fcz
   1    1       1000       1000       1000
#endif

; Include generic topology for ions
#include "ions.itp"

[ system ]
; Name
Protein in water

[ molecules ]
; Compound        #mols
protein             1
extra_nacl          1
SOL             14083