On Mon, Jun 29, 2020 at 2:34 PM Matias Machado <mmachado.pasteur.edu.uy> wrote:
>
> You are right Daniel, there is clearly no need for such parameter... however leap demands it in other cases (e.g. cyclopropane)... so there must be a magic hand behind such selectivity as the info isn't defined in frcmod files...
Indeed! If you look at the LEaP source code you will find the
following function (I love the comment!):
/*
* zbUnitIgnoreAngle
*
* Author: Christian Schafmeister (1991)
*
* This is an ungodly hack that checks if the types are defining
* an angle interaction between HW-HW-OW. If they are then return TRUE
* this will cause the code to ignore this interaction.
* This will allow LEAP to handle TIP3 waters.
The function also has some logic to handle extra points stuff.
(Honestly, what a workhorse LEaP has been!).
-Dan
>
> ----- Mensaje original -----
> De: "Daniel Roe" <daniel.r.roe.gmail.com>
> Para: "AMBER Mailing List" <amber.ambermd.org>
> Enviados: Lunes, 29 de Junio 2020 14:54:57
> Asunto: Re: [AMBER] ff14SBonlysc + OPC3
>
> On Mon, Jun 29, 2020 at 1:03 PM Matias Machado <mmachado.pasteur.edu.uy> wrote:
> > An additional curiosity, neither "frcmod.opc3" nor "frcmod.tip3p" have angle definitions, I mean there is no angle at all, not even set to zero!
>
> Note this is by design since TIP3P and OPC are rigid water models.
> There is a "bond" between the hydrogens instead of an H-O-H angle.
> This just makes it easier to apply the constraints to keep the water
> rigid.
>
> -Dan
>
> _______________________________________________
> AMBER mailing list
> AMBER.ambermd.org
> http://lists.ambermd.org/mailman/listinfo/amber
>
> _______________________________________________
> AMBER mailing list
> AMBER.ambermd.org
> http://lists.ambermd.org/mailman/listinfo/amber
_______________________________________________
AMBER mailing list
AMBER.ambermd.org
http://lists.ambermd.org/mailman/listinfo/amber
Received on Mon Jun 29 2020 - 17:30:02 PDT
