Spin-spin interaction

General forum for EasySpin: questions, how to's, etc.
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Geraldine
Newbie
Posts: 3
Joined: Mon Jul 28, 2014 11:40 am

Spin-spin interaction

Post by Geraldine »

Hi,

I have been using the Sys.ee function to simulate spin-spin interaction in my system. For example, I wrote:
Sys.S = [1 1];
Sys.g = [2.0004 ; 2.0004];
Sys.lwpp = 0.5;
Sys.ee = [1 1 2]*270
It fits well the experimental data but I am not sure about the meaning of [1 1 2]*270. Can you help me ? Does it mean that the interaction is worth 2*270=540 MHz ?
Thank you very much for your help,
Cheers,
Geraldine
Stefan Stoll
EasySpin Creator
Posts: 1041
Joined: Mon Jul 21, 2014 10:11 pm
Location: University of Washington

Re: Spin-spin interaction

Post by Stefan Stoll »

Sys.ee includes all forms of electron-electron interactions, no matter what the physical origin is.
Check out the corresponding ES documentation.

Did you mean [-1 -1 2]*270? If yes, this is just the through-space dipolar coupling between two electron spins,
aligned along the z axis.
Geraldine
Newbie
Posts: 3
Joined: Mon Jul 28, 2014 11:40 am

Re: Spin-spin interaction

Post by Geraldine »

No, I really meant [1 1 2]*270 ...
What about the value of the coupling ? Is it 540 MHz ?
Thanks,
Matt Krzyaniak
EasySpin Guru
Posts: 153
Joined: Tue Jul 22, 2014 11:01 am
Location: Northwestern University

Re: Spin-spin interaction

Post by Matt Krzyaniak »

Geraldine wrote:No, I really meant [1 1 2]*270 ...
What about the value of the coupling ? Is it 540 MHz ?
Thanks,

Code: Select all

Jiso = sum([1 1 2]*270)/3 = 360
Jdip  = [1 1 2]*270 - Jiso = [ -90 -90 180] = 90*[-1 -1 2] 
So you have a 360 MHz isotropic(Heisenberg exchange) coupling and a 90 MHz dipole coupling.
Geraldine
Newbie
Posts: 3
Joined: Mon Jul 28, 2014 11:40 am

Re: Spin-spin interaction

Post by Geraldine »

Great !
Many thanks !!!!!
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