[gmx-users] Re: help with improper angle in gmx

[Tom]

Thanks for your reply, Justin!

I knew that gmx use as the follows for opls aa:
--------------------
; Improper OPLS dihedrals to keep groups planar.
; (OPLS doesnt use impropers for chiral atoms).
; Since these functions are periodic of the form 1-cos(2*x), they are
actually
; implemented as proper dihedrals [1+cos(2*x+180)] for the moment,
; to keep things compatible.
; The defines are used in ffoplsaa.rtp or directly in your .top file.

; O?-C -X -Y improper torsion. C can be C_2 or C_3 too.
#define improper_O_C_X_Y        180.0     43.93200   2
--------------------

But if it is possible to choose the function type:   harmonic type  (f.t y.
=2)
Where to assign function type number? Thanks!

Tao

On Mon, Jan 7, 2013 at 7:48 PM, <gmx-users-request at gromacs.org> wrote:

> Re: help with improper angle in gmx (Justin Lemkul)