Computes spin Hamiltonians for the manifolds of an exchange-coupled spin pair in the strong-exchange limit.

CSys = spinladder(Sys)
[CSys,En] = spinladder(Sys)
... = spinladder(Sys,Temp)
spinladder(...)

Given a exchange-coupled two-electron-spin system in Sys, this function computes the spin Hamiltonians for the various spin manifolds in the coupled representation, incl. g, A and D tensors, assuming the strong-exchange limit.

CSys is a cell array that contains the coupled-spin systems sorted by energy. En contains the center-of-gravity energies as determined by the exchange coupling. If no output is requested, spinladder prints some information about the coupled manifolds.

If a temperature (in kelvin) is given, populations for each manifold are computed and returned in the fields CSys{:}.weight. These populations are total populations for the manifold, and not per-level populations.

Here is the coupling of a Mn(II) dimer. The uncoupled spin system is

Sys.S = [5/2 5/2];
Sys.g = [2 2];
Sys.A = [250 0; 0 250];
Sys.Nucs = '55Mn,55Mn';
Sys.D = [1 1]*-2.3*30e3;
Sys.J = -30*30e3;

Calling spinladder for this system with a temperature of 293 K, but without output yields

spinladder(Sys,293)

S1 = 2.5, S2 = 2.5 (total 12 electronic states)
6 manifolds:
  S = 0 (1 electronic states)
     energy 7875 GHz, population 0.00592/state, 0.00592 total
  S = 1 (3 electronic states)
     energy 6975 GHz, population 0.00686/state, 0.0206 total
  S = 2 (5 electronic states)
     energy 5175 GHz, population 0.00921/state, 0.0461 total
  S = 3 (7 electronic states)
     energy 2475 GHz, population 0.0143/state, 0.1 total
  S = 4 (9 electronic states)
     energy -1125 GHz, population 0.0259/state, 0.233 total
  S = 5 (11 electronic states)
     energy -5625 GHz, population 0.054/state, 0.594 total

spinladder computes the magnetic parameters for the individual manifold spins in the coupled representation.

CSys = spinladder(Sys,293);
CSys{2}

ans = 
         S: 4
         g: 2
         D: [6.5714e+003 6.5714e+003 -1.3143e+004]
        ee: -900000
      lwpp: 4
    weight: 0.2327

spinladder uses expressions from the Bencini/Gatteschi book, p.53-54, derived under the assumption that the isotropic exchange interaction is much larger than any other interaction in the system (strong-exchange limit).

This means that spinladder cannot be used for spin systems with intermediate or weak exchange.