Simulartion with inhomogeneous Field

[Mengjia He]

Hi, Prof. Kuprov,

Here is a question regards proccessing inhomogeneous B0 within the liquid NMR simulation.

A direct way is updating the 'spin_system.inter.zeeman.matrix' and running the simulation for each voxel, like the script below. But it will cause long program in multiple spins case.

So I want to ask if there is any interface in Spinach, that I can define the spin_system quickly.

Thank you.
Mengjia

[kuprov]

I would recommend setting the magnetic field to 1 Tesla in the sys.magnet, and then requesting separately the Zeeman part and the coupling part of the Hamiltonian by using the retention options described here:

https://spindynamics.org/wiki/index.php?title=Assume.m

that way you only need to build the Hamiltonians once. Then combine them into H=Hc+B*Hz where B is your actual field in Tesla. Then use that to run the simulation of your choice with that Hamiltonian.

For integrating over the field distribution, I recommend the Gauss-Legendre quadrature:

https://spindynamics.org/wiki/index.php ... Gaussleg.m

[Mengjia He]

Sounds nice way, I would try.