AMBER Archive (2006)

Subject: RE: AMBER: Antechamber RESP charges do not sum to zero even with -nc 0 flag

From: Junmei Wang (jwang_at_encysive.com)
Date: Fri Jul 07 2006 - 12:04:00 CDT

Actually, at least since amber8 there are five decimal places for
charges in prepi and prepc formats. In the latest version of antechamber
(to be posted) six decimal places are used for charges in prepi, prepc,
mol2 and ac formats. I don't think a net charge of 0.004 will affect
your results much.

Regards

Junmei

-----Original Message-----
From: owner-amber_at_scripps.edu [mailto:owner-amber_at_scripps.edu] On Behalf
Of Bob Johnson
Sent: Friday, July 07, 2006 9:56 AM
To: amber_at_scripps.edu
Subject: AMBER: Antechamber RESP charges do not sum to zero even with
-nc 0 flag

Hello everyone,
I am trying to generate a force field for trimethylamine. I have
optimized the geometry and obtained the charges using Gaussian 03. I
then execute the following command to assign RESP charges using
antechamber: antechamber -i tma-resp.log -fi gout -o tma.prepin -fo
prepi -c resp -nc 0

The assigned charges are reasonable except that the total charge of the
molecule is 0.004e. It seems that if antechamber kept 4 decimal places,
the assigned charges would be closer to zero. Any ideas how to fix this?
Thanks, Bob Johnson PhD Student Department of Physics & Astronomy
University of Pennsylvania
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