Re: [AMBER] CPPTRAJ cannot open RXSGLD trajectories out of the box

From: Daniel Roe <>
Date: Sun, 7 Feb 2021 09:38:11 -0500


On Sun, Feb 7, 2021 at 9:00 AM Charo del Genio <> wrote:
> Dear all,
> it appears that CPPTRAJ is unable to open RXSGLD trajectories, as it does not recognize rxsgldtraj and rxsgldid as valid keywords. It does work, however, if I replace the keywords with remdtraj and
> remtrajidx, respectively, effectively treating the trajectories as if they were T-REMD. Is this intended behaviour? If so, the manual should perhaps be updated. If not, are there any unintended
> consequences in doing so?

Indeed, rxsgldtraj and rxsglid are not valid keywords for 'trajin',
which is why cpptraj does not recognize them. The 'remdtraj' keyword
is not in fact specific to T-REMD (although it started that way a long
time ago in ptraj). From the manual:

"[remdtraj] Read <filename> as the first replica in a group of replica

So to sum up, 'remdtraj' and 'remdtrajidx' should work for
trajectories from any type of REMD. Let me know if you see otherwise.

Hope this helps,


> Cheers
> Charo
> --
> Dr. Charo I. del Genio
> Senior Lecturer in Statistical Physics
> Applied Mathematics Research Centre (AMRC)
> Design Hub
> Coventry University Technology Park
> Coventry CV1 5FB
> UK
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Received on Sun Feb 07 2021 - 07:00:02 PST
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