[gmx-users] What if there are multi-definition of dihedrals?

[Yang Ye]

Entries in [ bonds ], [ pairs ], [ angles ], [ dihedrals ] are additive. 
Repeat the entry for two or more times will effectively double or triple 
the energy.

On 7/17/2007 3:02 PM, Tsjerk Wassenaar wrote:
> Hi Wu Yanbin,
>
> Multiple definitions are combined. (Isn't this in the manual?)
>
> Tsjerk
>
> On 7/17/07, WU Yanbin <wuyb02 at gmail.com> wrote:
>> Hi, All,
>>   If there are multi-definitions of the same dihedral in topology 
>> file, how
>> will gromacs treat it? Using the second one, or the addition of the two
>> items?
>>   The reason for my asking this is: a dihedral potential function 
>> like the
>> following needs to be realized ,
>>   V = sum(Cn*cos(phi)^n), n=1, 2, 3, 4, 5, 6.
>>   But the RB function in gromacs is limited for n up to 5.
>>   If multi-definition is considered as addition, the potential 
>> function can
>> be splitted into two, one using RB function and the other using proper
>> dihedral funciton with n=6.
>>   If not, can anyone recommend one solution? Thanks.
>>
>> Yours Sincerely,
>>
>>         WU Yanbin
>>
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>
>