VMD-L Mailing List

From: Mayne, Christopher G (cmayne2_at_illinois.edu)
Date: Fri Jun 07 2013 - 09:29:16 CDT

Another relevant question is if all of the bounds can be satisfied simultaneously; if the bound windows are small, this might not be possible. Since the charge of the last group is computed to bring the total system charge to the specified integer charge, this is where one would see the bound violation.

Regards,
Christopher Mayne

On Jun 7, 2013, at 7:40 AM, JC Gumbart wrote:

Did the optimization actually converge or just reach the maximum number of iterations? It should be impossible to violate the last bound for a converged calculation, but for an individual step it’s certainly possible.

From: owner-vmd-l_at_ks.uiuc.edu<mailto:owner-vmd-l_at_ks.uiuc.edu> [mailto:owner-vmd-l_at_ks.uiuc.edu] On Behalf Of Wenhao Liu
Sent: Thursday, June 06, 2013 10:59 PM
To: Vmd l
Subject: vmd-l: charge exceed the range between Low bound and High bound in ffTK charge optimization

Hi vmd people,
When I am doing the charge optimization by using ffTK plugin, I set the Low bound and High bound for all atoms in my system, the optimized result showed that all atoms are within their range except the last atom in charge group. I set that oxygen's range from -0.9 to -0.8 but it gave me -0.5 result. I was quite confused that how can this happen? Looking forward to your ideas!

Wenhao