Re: [AMBER] external electric field in Amber 16

From: michal biler <>
Date: Tue, 30 May 2017 23:06:04 +0200 (CEST)

I see. Setting ntb = 1 should keep constant V. Anyway, this is still the
case with no pressure scaling: ntp = 0 (as external electric field cannot be
apperantly used when npt 0). What if I need to delete one molecule per each
frame (to simulate evaporation), therefore pressure has to be taken into
account and has to be equilibrated while using the electric field? How
should I proceed?

Message: 19
Date: Tue, 30 May 2017 10:43:23 -0400
From: Carlos Simmerling <>
Subject: Re: [AMBER] external electric field in Amber 16
To: AMBER Mailing List <>
Content-Type: text/plain; charset="UTF-8"

your system shouldn't explode at constant volume. are you sure you have ntb
set right? If it is unstable at constant V, make sure you equilibrate a
while at constant P, then switch to constant V.

On Tue, May 30, 2017 at 10:39 AM, michal biler <>

> Dear Amber users,
> I want to use an external electric field in Amber 16. After specifying efz

> values, I got this error message:
> | ERROR: External electric fields cannot be used when npt > 0!
> If I turn off the pressure scalling (ntp = 0), the simulation runs, but of

> course, the system is kind of exploding as I do not have any pressure.
> I found a link to the similar question (

> 0126.html) ...anyway, is there a way how to do such simulations with both
> external electric field and pressure on? I think, long simulations would
> not
> make a sense without ntp.
> Thank you!
> Michal
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Received on Tue May 30 2017 - 14:30:03 PDT
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