[gmx-users] How to use "define = -DPOSRES" in Gromacs 2018?

[ZHANG Cheng]

My backbone restraints is shown in the "Protein_A.itp" file:



#ifdef POSRES
#ifndef POSRES_FC
#define POSRES_FC 1000.00
#endif
 [ position_restraints ]
      1    1    POSRES_FC    POSRES_FC    POSRES_FC
      3    1    POSRES_FC    POSRES_FC    POSRES_FC
      5    1    POSRES_FC    POSRES_FC    POSRES_FC
......
    162    1    POSRES_FC    POSRES_FC    POSRES_FC
    163    1    POSRES_FC    POSRES_FC    POSRES_FC
#endif




The Martini protein tutorial said: specify "define = -DPOSRES" in the mdp file for "gmx grompp".


However, adding "define = -DPOSRES" to the mdp file causes the error:




Fatal error:
Cannot find position restraint file restraint.gro (option -r).
From GROMACS-2018, you need to specify the position restraint coordinate files
explicitly to avoid mistakes, although you can still use the same file as you
specify for the -c option.




The tutorial uses Gromacs 5, but I am using Gromacs 2018. Is this the problem for that?


How can I trigger those restraints in "Protein_A.itp" file using Gromacs 2018?