From: Mayne, Christopher G (cmayne2_at_illinois.edu)
Date: Wed Apr 17 2013 - 09:52:43 CDT

I don't think so. The optimizer judges the ability of a charge set to reproduce the interaction, but the positioning of the water is predetermined based on geometry, i.e., not a stochastic calculation. The best time to modify your weights is when you want to bias the charge sets towards getting a particular interaction correct (relative to qm).

On Apr 17, 2013, at 9:18 AM, "Wenhao Liu" <mdsimulate_at_gmail.com<mailto:mdsimulate_at_gmail.com>> wrote:

Chris,
So you mean I can set the weight like to 2 when I deal with oxygen-water bonding in the condition that oxygen in my new molecule can form two hydrogen bonds with water? Thank you!

Wenhao

$B:_(B 2013$BG/(B4$B7n(B17$BF|@14|;0!$(BMayne, Christopher G $B<LF;!'(B
It is not required due to the symmetry of water--there is no extra information to be gained by flipping the identities of the hydrogens. ffTK handles the positioning of the water automatically.

Regards,
Christopher Mayne

On Apr 17, 2013, at 1:53 AM, Wenhao Liu wrote:

> Hello vmd people,
> I was just wondering is it required to set up more than 1 hydrogen bonding for Acceptor (like the oxygen that can bonding with 2 hydrogen of the water) when I need to do the water interaction Gaussian calculation in charge optimization step? But I can only have 1 possible conformation to put water molecule bonding with oxygen in Acceptor indices, the other possible hydrogen boding between oxygen and hydrogen of water should be in different orientation, right? Or I can just set the weight of this calculation to 2 when I do the charge optimization? Thanks in advance.
>
> Wenhao