AMBER Archive (2004)

Subject: Re: AMBER: Why the charge is not an integer?

From: FyD (
Date: Sun Dec 12 2004 - 13:47:02 CST

> Total unperturbed charge: 6.9985
> Total perturbed charge: 6.9985
> Here comes the problem ,the charge of my molecular is not an integer.
> So when I try to add Cl- ions to neutralize the system,only 6 ions are
> added.Thus the net charge is 0.9985.
> Where does the fractional charge come from?And how can I neutralize the
> system?

This means you have an error of .0015 in one of your LEaP units. I think it is
too big to be a rounding off error generated by RESP... There is something
wrong in one of your units. You can still neutralize this unit manually by
adding .0015 to this unit but I would check first why you have such error...

Regards, Francois
The AMBER Mail Reflector
To post, send mail to
To unsubscribe, send "unsubscribe amber" to