[gmx-users] How to extend Ryckaert-Bellemans parameters?

Nicolas Sapay nsapay at ucalgary.ca
Tue Mar 20 23:14:37 CET 2007

David van der Spoel wrote:
> Nicolas Sapay wrote:
>> Hello everybody,
>> I need to extend Ryckaert-Bellemans parameters to C6 in order to take 
>> into account dihedrals in alkyl chains. What parts of the source code 
>> need to be modified exactly? I'm sure it is pretty trivial to do 
>> that, but I can't find by myself the functions and/or structures 
>> involved in the R-B potential calculation. Can someone help me? I 
>> have already a .itp file with the correct number of parameters.
>> Nicolas
>> ps: I have read the previous posts on the topic... Unfortunately, the 
>> parts of the code to modify were not indicated.
> You can actually do it simpler. By adding a proper dihedral with 
> multiplicity 6 in the top file. You then have two dihedral functions 
> on one bond.
Thanks for your quick answer,

As it is not possible to do that in the ffxxxbon.itp file, I was sure it 
was the same thing in all other files. But it works perfectly with my 
.top files... Thanks!


[ Nicolas SAPAY, Ph.D. ]
University of Calgary, Dept. of Biological Sciences
2500 University drive NW, Calgary AB, T2N 1N4, Canada
Tel: (403) 220-6869
Fax: (403) 289-9311

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