Re: [AMBER] "vlimit exceeded" in NVT simulation

From: Pratul Agarwal <>
Date: Tue, 8 Jan 2019 15:24:14 +0000


This type of message indicates that one or more of your atoms are experiencing abnormally large force(s). Most common reason is that the conformation is unphysical with close contacts (steric clashes). Check your starting structure to see if things looks reasonable. Apart from making sure that the starting structure is reasonable, you should also check the temperature value. What is starting temperature value for your simulation? High value of temperature can indicate unstable simulation.

One thing you could try is using small time-step and see if system stabilizes. Once things are stable you could switch to longer time-step.


Pratul K. Agarwal, Ph.D.
(Editorial Board Member: PLoS ONE, Microbial Cell Factories)

On 1/8/2019 10:07 AM, Lucas Bandeira wrote:

Dear AMBER community,

I'm performing a NVT simulation in a system composed by a Au slab of 2 x 2
x 2 nm and "vaccum box" of 2 x 2 x 3 nm, thus the total volume of the slab
is 2 x 2 x 5 nm. From the step 200 I got the error "vlimit exceed for step
...". I've performed a minimization before the NVT and the RMS was to the
power of (-5), thus I think the energy is minimized. Could one help me with
this problem?

Thank you in advance,

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Received on Tue Jan 08 2019 - 07:30:03 PST
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