Re: [AMBER] Why is 360 degree is not equal to 0 degree in PES Scan?

From: Lorenzo Gontrani <>
Date: Sun, 12 Apr 2020 17:11:02 +0200

Actually, the two ab initio extrema don't seem equal either. The thing I
can think of is a strong effect of the other degrees of freedom when you do
a relaxed PES scan.. depending on the path you follow, the systems keep a
sort of "memory" of the previous point and you can arrive at slightly
different mininima of the PES that share the same fixed dihedral,depending
on the direction from which you arrive. Clearly, this can happen if the
system has many DOF, something more complex than ethane or buthane!
I would try to reduce the numbers of variables to concentrate on the
dihedral of interest.
Also try to scan between -180 and +180, and/or other ranges with the same

Il sab 11 apr 2020, 01:03 Erdem Yeler <> ha scritto:

> Hello,
> I parameterized a novel molecule and I sent it a as an article to
> journal and my article has been rejected.
> Here is my PES scan of x-y-z-t dihedral .
> [link for the picture: ]
> [image: image.png]
> the referee says: "There is a strange transition at ~130° as well as a
> very large discontinuity at Φ = 0° and 360°. It is expected that
> Edihedral(0°) = Edihedral(360°); the green and yellow dotted lines in the
> plot below should be at the same level, but this does not seem to be the
> case"
> Actually I performed PES scan in gaussian09 and psi4 and I got the same
> results in different softwares so I thought this chart is not strange.
> Still I am not sure if referee is right or not. Before I send the article I
> saw some parameterization articles which didn't perform PES scan 0-360
> degree. Some of authors performed scan in the range of 0-60 degree or
> 0-120 exc.. degree and I didn't predict I will face a result like this.
> Should I perform single point energy for each angle instead of PES scan?
> or should I do another thing? What are your suggestions? How can I explain
> this?
> Thank you.
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Received on Sun Apr 12 2020 - 08:30:02 PDT
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