[gmx-users] dihedral type equation

Mark Abraham Mark.Abraham at anu.edu.au
Wed Aug 22 02:00:15 CEST 2012

On 22/08/2012 3:33 AM, tarak karmakar wrote:
> Dear All,
> I am using AMBER94 force-field for my protein. In the original force
> field paper the dihedral functional form has been given as (V/2)[ 1 +
> cos(nPhi - gamma)]   but in GROMACS(4.5.4) manual I see the (1/2)
> factor is not there [ eq 4.62]. So is this internally handled in
> GROMACS or should I worry about this half-factor ?

Probably folded into the force constant. You'll have to compare the 

> Can anyone inform me the functional forms for proper dihedral types
> '1' , '4' and '9'. If I understand correctly the functional form which
> I have mentioned earlier is of type '9'.

Table 5.5


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