question on the weakly coupled MnIII-MnIV dimer

[sejerng]

I have a question on the weakly coupled MnIII-MnIV dimer simulation.

I would like to simulate the parameters from reference paper.

The given parameters are as follows:

MnIII, MnIV
g(perp) = 2.01, g(para)= 1.93,
A(III) = (-375, -375, -412) MHz, A(IV) = (145,145,402) Mhz
which correspond to intrinsic parameters a(III) = (-230,-230,-150) MHz,
D = -4 cm-l (for Mn(III)), J = -10 cm-I, a(Iv) = -230 MHz

According to the Mn dimer example in the easy spin website, I inserted those parameters and tried to simulate as follows

Sys.S = [4/2 3/2]
Sys.g = [2 2]
Sys.A = [-375 -412; 145 402]
Sys.Nucs = '55Mn, 55Mn'
Sys.D = [1 0]*-4*30e3
Sys.ee = -10*30e3

My question is :

1. about A tensor, I would like to apply three parameters each but it doesn't work.

2, About D, [1 0]*-4*30e3
Does it mean zerofield splitting of -4 cm-1 to MnIII, and 0 to MnIV each?
I would like to give different zero field splitting to each species.

3. In addition to those problems, our personal computer cannot simulate the dimer example in the website. If we try to run the example, the computer works for about 20 min and an error message saying 'short of memory' comes out. Thus, we are using 'hybrid' option. Is it OK?

I would appreciate if you please help me to solve this problem.

Thank you very much.

Sung Eun Jerng

[Stefan Stoll]

What is the reference you are mentioning?

1. To specify the three-component hyperfine tensors, it's important to realize that the first nucleus is only coupled to the first electron spin, and the second nucleus is only coupled to the second electron spin:

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Sys.A = [-375 -375 -412, 0 0 0; 0 0 0, 145 145 402];

2. Yes, that's correct.

3. The Opt.Method = 'hybrid' option should work well in this case.

Also, make sure to compare the definition of the isotropic exchange coupling in the paper with the one of EasySpin (+J*S1*S2).

[sejerng]

Thank you so much for your help!

The reference paper was 'Inorg. Chem. 1994, 33, 382-387' in which they simulated the weakly coupled Mn III/IV dimer.
I wanted to try those parameters.

Thank you again!

sincerely yours,
Sung Eun Jerng