[gmx-users] interaction potential parameters and the forcefield.itp file

[akari karin]

dear gromacs users,
i am simulating carbon nanotubes. i am having some problems with my
interaction potential in the forcefield.itp file.
my forcefield.itp file looks like this-

[ defaults ]
; nbfunc        comb-rule       gen-pairs       fudgeLJ fudgeQQ
1               3               yes             0.5     0.5

[ atomtypes ]
; The charges here will be overwritten by those in the rtp file
; name       mass      charge    ptype      sigma      eps
  CJ   6     12.01100     0.000       A    3.40000e-01  3.60000e-01 ;
  HJ   1     1.00800      0.417        A    0            0         ;

[ bondtypes ]

; i    j func        b0          kb
  CJ    CJ      1    0.14000   478900.0   ; TRP,TYR,PHE
  CJ    HJ      1    0.10800   307105.6   ; PHE, etc.

[ angletypes ]
  CJ     CJ     CJ      1   120.000    562.200   ; PHE(OL)
  CJ     CJ     HJ      1   120.000    292.880   ;
  HJ     CJ     HJ      1   117.000    292.880   ; wlj from HC-CM-HC

[ dihedraltypes ]
  CJ     CJ     CJ     CJ      3     30.33400   0.00000 -30.33400
0.00000   0.00000   0.00000 ; aromatic ring
  HJ     CJ     CJ     HJ      3     30.33400   0.00000 -30.33400
0.00000   0.00000   0.00000 ; aromatic ring
  HJ     CJ     CJ     CJ      3     30.33400   0.00000 -30.33400
0.00000   0.00000   0.00000 ; aromatic ring



(i took it directly from chembytes)


i have a few questions regarding this.

1. how should i input my torsion parameters? i saw in the manual that i
should put it in the [ dihedraltypes ] but
if i use functiontype of 3 i have 5 columns and i don't understand what
each part means.

2.i could input my morse bond potentials (Kcr and rc) but could not find
the place to input gamma. where should i put it?

thanks in advance.