[gmx-users] desciption of ffG43a1bon.itp

[Mark Abraham]

subarna thakur wrote:
> Hello
> In the file ffG43a1bon.itp, the bond parameters are given like this-
> ------------------------------
> ICB(H)[N] CB[N] B0[N]
> ;
> #define gb_1 0.     1000 1.5700e+07
> ; H - OA        750 
> ;
> #define gb_2 0.     1000 1.8700e+07
> ; H - N (all)     895 
> ;
> #define gb_3 0.    1090  1.2300e+07
> ; HC - C        700 
> ------------------------------------
> Can anybody please tell me, which one is is the force constant and which one is ideal bond length. For describing a new bond parameters , what the values 
> I have to provide in the file ffG43a1bon.itp.
> The ffG43a1bon.itp is not clearly described in the chapter5 of the manual of gromacs version4.

Table 5.4 describes the format necessary for bonded parameters. The 
above define C preprocessor macros that insert the corresponding text 
wherever they are used. You should look up where they are used to find 
their context, and then infer from Table 5.4 what the values mean. None 
of them look like real bond lengths.

Mark