High-order zfs, wignerd

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Mantas_Sim
Newbie
Posts: 7
Joined: Mon Sep 21, 2015 2:12 pm

High-order zfs, wignerd

Post by Mantas_Sim »

Hi!

I am trying to simulate a Mn2+ spectrum with higher order zfs parameters B(k,q). In the manual it is written that currently it is not possible to include tilt angles for the principal frames of these higher order tensors. But there is an option provided to use Wigner rotation matrices:

"Alternatively, you can use wignerd to compute a Wigner rotation matrix that can be used to tilt the tensors explicitly.
angles = rand(1,3)*pi; % Euler tilt angles, in radians
B2 = [3 4 5 0 2]; % B(2,q) tensor components
R = wignerd(2,angles); % rotation matrix for rank-2 tensor
B2 = R*B2; % rotated tensor
Sys.B2 = B2.';"

Here I see two problems. First of all, shouldn't B2 = R*B2 be B2 = R*B2' ? Secondly, wignerd provides complex rotation matrix which then is multiplied by B2 giving complex components of Sys.B2. But those should be real. Is this a just a mistake in the manual? How to tilt the higher-order tensors then?

Thanks!
Mantas
Stefan Stoll
EasySpin Creator
Posts: 1041
Joined: Mon Jul 21, 2014 10:11 pm
Location: University of Washington

Re: High-order zfs, wignerd

Post by Stefan Stoll »

This is indeed not correct. There needs to be a transpose, and the rotation should not give a complex-valued result, since we are not using spherical tensor operators, but the tesseral linear combinations of them.

We will fix this. Thanks for reporting!
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