# Doublerot.m

Fokker-Planck double angle spinning context. Generates a Liouvillian superoperator and passes it on to the pulse sequence function, which should be supplied as a handle. Syntax:

  answer=doublerot(spin_system,pulse_sequence,parameters,assumptions)


where pulse sequence is a function handle to one of the pulse sequences located in the experiments directory, assumptions is a string that would be passed to assume.m when the Hamiltonian is built and parameters is a structure with the following subfields:

  parameters.rate_outer - outer rotor spinning rate in Hz

  parameters.rate_inner - inner rotor spinning rate in Hz

  parameters.axis_outer - spinning axis of the outer rotor,
given as a normalized 3-element
vector

  parameters.axis_inner - spinning axis of the inner rotor,
given as a normalized 3-element
vector

  parameters.rank_outer - maximum harmonic rank to retain in
the solution (increase till conver-
gence is achieved, approximately
equal to the number of spinning si-
debands in the spectrum) for the
outer rotor

  parameters.rank_inner - maximum harmonic rank to retain in
the solution (increase till conver-
gence is achieved, approximately
equal to the number of spinning si-
debands in the spectrum) for the
inner rotor

  parameters.rframes  - rotating frame specification, e.g.
{{'13C',2},{'14N,3}} requests second
order rotating frame transformation
with respect to carbon-13 and third
order rotating frame transformation
with respect to nitrogen-14


Additional subfields may be required by the pulse sequence. The parameters structure is passed to the pulse sequence with the following additional parameters set:

  parameters.spc_dim  - matrix dimension for the spatial
dynamics subspace

  parameters.spn_dim  - matrix dimension for the spin
dynamics subspace


This function returns the powder average of whatever it is that the pulse sequence returns.

Note: arbitrary order rotating frame transformation is supported, inc- luding infinite order. See the header of rotframe.m for further information.

Note: the state projector assumes a powder -- single crystal DOR is not currently supported.