[gmx-users] mutiple dihedral terms

[Justin A. Lemkul]

Sanku M wrote:
> Hi,
>   I have a molecule consisting of 4 atoms  1-2-3-4 .
> The paper parameterizing the molecule has reported combination of 
> following multiple set of dihedral terms by fitting the dihedral angle 
> distributions of this tetra-atomic molecule :
>       theta0         K     n
>     180           1.96   1 
>      0              0.18   2
>      0             0.33    3
>      0            0.12     4
> 
> Now, I was trying to incorporate this dihedral terms in my gromacs 
> topology file: My question is , is it possible to use Proper dihedral 
> angles  four time for the same dihdral angles :
> i.e
> If I write the dihedral part of  topology file in the following way, 
> will it be OK so that Gromacs will add them up ?
> [dihedrals]
> 1  2  3  4     1    180.00    1.96   1
> 1  2  3  4     1     0    0.18   2
> 1  2  3  4     1     0    0.33   3
> 1  2  3  4     1     0    0.12   4
> 
> Or, will it consider only the last one ? 

They are additive.  Surely this is in the manual somewhere.

-Justin

> If it is not the case, Am I supposed to convert them into Ryckert 
> Bellman type and sum them up ?
> Any suggestion will be helpful.
> Sanku
> 

-- 
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Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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