Re: [AMBER] Error running TI with pmemd.cuda: "Error: an illegal memory access was encountered launching kernel kClearTIKinEnergy_kernel"

From: Rafał Madaj <>
Date: Tue, 21 Dec 2021 08:56:42 +0100

Hi Ali,

I encountered this problem when /lambda/ was close to boundary values
(either 0 or 1).
As far as I remember, it is due to zero appearing in denominator when
calculating energy according to formula used in TI. As we have
stochastic calculations it may appear that it sometimes does not
encounter this problem.

My workaround for this was just ignoring the faulty calculations and
after all simulations either removing faulty /lambda/, or manually
fitting the energy values by interpolation from polynomial regression
(in excel or something similar).

However, if it fails at other points too, make sure your system is in

Is your timestep set to 1 or 2 fs? Including equilibration period.



On 20.12.2021 22:50, Ali Morshedi wrote:
> Hi all,
> When running TI MD simulations using pmemd.cuda, I sometimes get the
> following error after some steps:
> Error: an illegal memory access was encountered launching kernel
> kClearTIKinEnergy_kernel
> What's strange is that it's not reproducible. Meaning if I run the
> simulation again, it might finish without the error ! Also energy,
> temperature etc are all normal at the step that the error occurs.
> I'd appreciate it if you let me know any information you might have
> about this.
> Thanks,
> Ali
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Received on Tue Dec 21 2021 - 00:00:02 PST
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