[gmx-users] Confusion about itp file generated by topolbuild

[Bikramjit Sharma]

Hi all,
I tried to generate topology file for benzene (as a trial)  using topolbuild1_3. The itp file generated is (ffben.itp in my case)


#define _FF_GAFF

#define _FF_AMBER
#define _FF_USER


[ defaults ]
;nbfunc     comb-rule      gen-pairs     fudgeLJ      fudgeQQ
  1               2               yes             0.5     0.8333


#include "ffbennb.itp"
#include "ffusernb.itp"
 
What is the meaning of first 3 lines? Because there is no force field with any of these names (appeared in those lines) in the working directory and we are not assigning any path. So I am confused. 


Also, following suggestions from gromacs user list (https://www.mail-archive.com/gmx-users@gromacs.org/msg12722.html), I have commented the last two lines of this itp file. So, the non bonded parameter file generated by topolbuild is not used.  Is it correct?


Thanks,
Regards,
Bikram