mesolve giving different results for same problem

[ph.al...@gmail.com]

Hello guys, I'm trying to use mesolve to study the influence of a magnetic field in singlet and triplet states. I'm defining the hamiltonian in two different ways, but physically they mean the same thing and I don't know which is the right result.

In one I'm defining similarly to a time-dependent hamiltonian, but removing the time-dependency.

H0 = Hamiltonian(theta, B, A)

H1 = RF_Hamiltonian(exchange)

def H1_coeff(t, args):

    return B_RF*mT2nev

H = [H0, [H1, H1_coeff]]

result = mesolve(H, y0, t_eval, L_ops, options=opts)

In the other I'm just defining a combinations of hamiltonians.

H_External = B_RF*mT2nev*RF_Hamiltonian(exchange)

result =  mesolve([H0, H_External], y0, t_eval, L_ops, options=opts)

Shouldn't they give the same results? Which approach should I use?

[Simon Cross]

Yes, I would broadly expect these to give the results. To give more
concrete debugging suggestions though it would be useful to have a
complete minimal code snippet to run.