[gmx-users] User-defined potentials.

[David van der Spoel]

On Wed, 28 Nov 2001, Ram'on Garc'ia Fern'andez wrote:

>On Wed, Nov 28, 2001 at 06:02:45PM +0100, David van der Spoel wrote:
>> On Tue, 27 Nov 2001, Ram'on Garc'ia Fern'andez wrote:
>> >I suppose that the user defined potential is not automatically applied
>> >to all pairs of any type of atoms.
>> Yes it is. Your only variation is the force field parameters.
>
>I think that I do not understand you. What variation of force field
>parameters is posible? If I am using user-defined potentials, all the
>kinds of atoms will be subject to the same interactions. No parameters
>can change that. What am I overlooking?
The interaction potential is then:

Vij(r) = Aij f(r) + Bij g(r) + (qi qj/4 pi eps0) h(r)

For normal LJ/Coul that would be f(r) = r^-12; g(r) = r^-6; h(r) = 1/r
Your parameters Aij, Bij depend on atomtype, and qi, qj are the charges.

So, same functional form, different forcefield parameters.

Groeten, David.
________________________________________________________________________
Dr. David van der Spoel, 	Biomedical center, Dept. of Biochemistry
Husargatan 3, Box 576,  	75123 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://zorn.bmc.uu.se/~spoel
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