Third-order g tensor

[shiki_chen]

Dear developers,

I am currently handling a tricky system which is an S=2 system with extremely strong spin-orbit coupling. We have its high field EPR and normal X-band parallel mode EPR. Separated simulations of two spectra seem nice, however, we are not able to simultaneously simulate them with one spin Hamiltonian parameter set. Due to its strong spin-orbit coupling, we suspect that it may be necessary to take the third-order g tensor into consideration. I know that easyspin has higher-order operators, which allows the simulation to take 4th-order D tensor into account. However, I can not find any description of how to implement the 3rd-order g tensor during simulation.

Does easyspin support simulation with 3rd-order g tensor?

Thanks!

[Stefan Stoll]

EasySpin has these terms implemented, but they are not particularly well documented.

Use Sys.Ham310, Sys.Ham312, Sys.Ham314 to specify the parameters for a spin Hamiltonian term cubic in magnetic field (3) and linear in spin (1). The final digit 0, 2, 4 refers to the rank of the tensor. For B^3S term, there will be three tensors, one of rank 0, one of rank 2 and one of rank 4. If you are only interested in an isotropic term, the rank-0 term, with a single number, is sufficient.

To use this, you need version 6.0.0-dev.x, since 5.2.x won't work.

The function that implements this is ham_ezho, where ezho stands for "electron Zeeman higher order". The name of this function might change in the future. Look at it on the EasySpin GitHub repo to understand how it works. It uses spherical tensor operators akin to the Stevens operators.

[QiyiMiao]

Dear developer,

Thank you for your previous response regarding the simulation of B3S terms. However, I would greatly appreciate it if you could also provide guidance on the terms linear in magnetic field and cubic in spin (BS3). I've searched the Easyspin Github repo 'ham_ezho', but couldn't find these terms.

Thanks!

[Stefan Stoll]

Have a look here: https://github.com/StollLab/EasySpin/bl ... ham_ezho.m