model = sqw_spinw(sw, options) : 3D dispersion(HKL) spin-wave
iFunc/sqw_spinw: a 4D S(q,w) with a 3D HKL dispersion obtained from the
spinw package from S. Toth. A SpinW object must first be created, and is then
converted into an iFunc model for HKL evaluation. The intensity is computed
for a neutron scattering experiment.
MODEL CREATION:
To create the Model, the following syntax should be used:
s = sqw_spinw(sq, options);
or
s = sqw_spinw('CIF_filename', options);
with:
sq: a spinw object from <a href="https://www.psi.ch/spinw/spinw">SpinW</a>.
when omitted, use a square lattice Heisenberg Antiferromagnet with S = 1 and J = 1
options: a set of options to be used for the Model evaluation (structure)
options.component: the component to use as intensity, as documented in
<a href="matlab:doc sw_egrid">sw_egrid</a>
Default is 'Sperp'. Suggested is also 'Sxx+Syy+Szz'.
You can get a default model (squareAF) with:
s = sqw_spinw('defaults');
MODEL EVALUATION (once created):
Once the model is created, you may evaluate it using the standard evaluation call:
value = s(p, h,k,l,w)
or
f=iData(s,p,qh,qk,ql,w); % to get an iData object back
with:
p: sqw_spinw model parameters (double)
p(1)=Gamma energy broadening [meV]
p(2)=Temperature of the material [K]
p(3)=Amplitude
p(4...)= coupling parameters of the Hamiltonian
or p='guess'
qh: axis along QH in rlu (row,double)
qk: axis along QK in rlu (column,double)
ql: axis along QL in rlu (page,double)
w: axis along energy in meV (double)
signal: when values are given, a guess of the parameters is performed (double)
output: signal: model value
Example:
sq = sw_model('squareAF',2,0); % create the SW object
s = sqw_spinw(sq); % create the Model
qh = linspace(0.01,1.5,30);qk=qh; ql=qh'; w=linspace(0.01,10,50);
f = iData(s,s.p,qh,qk,ql,w); plot(log(f(:,:,1,:))); % evaluate and plot
Reference: https://en.wikipedia.org/wiki/Phonon
SpinW <https://github.com/tsdev/spinw>
<https://www.psi.ch/spinw/spinw>
S. Toth and B. Lake, J. Phys.: Condens. Matter 27, 166002 (2015).
Version: Nov. 26, 2018
See also iData, iFunc/fits, iFunc/plot, gauss, sqw_phonons, sqw_cubic_monoatomic, sqw_vaks, sqw_sine3d
<a href="matlab:doc(iFunc,'Models')">iFunc:Models</a>
(c) E.Farhi, ILL. License: EUPL.