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Posted: **Mon Jul 27, 2020 11:56 am**

Hello, EasySpin enthusiasts.

If I understand correctly, in pepper you can either rotate coordinates by CrystalFrame (MolFrame did not do anything for me), or use ordering potential that is centered around z axis of the lab frame, but you cannot use them simultaneously.

I am assuming that there are no (yet) functions to rotate the Ordering potential in pepper. If I construct a function that plots rotated potential, what would happen near xy plane in lab frame? Would pepper mirror it correctly? Since sphgrid with 'Ci' is the half-sphere (this is the largest manifold that sphgrid has), I wonder if I should manually reflect the ordering potential near the xy plane.

Thank you.

Posted: **Mon Aug 03, 2020 9:49 am**

What is the situation you are trying to simulate? Is it a oriented powder spectrum such as a partially aligned spin-labeled protein in a membrane, or a crystal spectrum with some disorder?

In EasySpin 5.2, it is not possible to rotate a sample with an orienting potential, since the orienting potential is defined with respect to the laboratory frame, and not with respect to a sample-fixed frame. This is a bug and design flaw, and we are working on fixing this for EasySpin 6. It's non-trivial, because it requires the overhaul of the entire frame system.

Some aspects of the new frame system are already available in the current development version of EasySpin 6. For example, there is the new field Exp.SampleRotation that makes it really easy to rotate a sample. You just specify the rotation angle rho and the lab-fixed rotation axis nRot_L:

Code: Select all

rho = pi/4;
Exp.SampleRotation = {rho,[0;1;0]};       % rotation around lab y axis (yL)
Exp.SampleRotation = {rho,'z'};           % rotation around lab z axis (zL)
Exp.SampleRotation = {rho,'x'};           % rotation around lab x axis (xL)

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Pepper: rotate ordering potential.

Pepper: rotate ordering potential.

Re: Pepper: rotate ordering potential.