Re: AMBER: ptraj dipole calculation in QMMM simulation

From: Gustavo Seabra <>
Date: Fri, 9 Feb 2007 13:54:04 -0500

Ptraj will use the charges from the prmtop file, **NOT** the Mulliken
charges from the QM/MM calculation.

If you want to use the charges from the QM calculation, what you can
do is to use 'printcharges=1' in the qmmm namelist . This will print
the Mulliken charges, but you will need to write your own program to
get the dipoles.

Can't tell you much about the units, though. I'd expect them to be in
Debye, but I'm not sure.

Good luck.


On 2/9/07, Evan Kelly <> wrote:
> Hi everyone,
> I am studying a QMMM system (quantum solute molecule in a box of TIP3P
> water) and was hoping to gain some electrostatic information about the
> solute. I can use ptraj to calculate the dipole moment of the solute, but
> can anyone tell HOW this is calculated? i.e. are the Mulliken charges used
> in a point charge dipole calculation? Does anyone know what units the
> dipole moment is outputted in?
> Thanks!
> ----------------------------------
> Evan Kelly
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Received on Sun Feb 11 2007 - 06:07:36 PST
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