gives the symmetry allowed matrices for a given coupling or anisotropy
aMat = GETMATRIX(obj, 'Option1', Value1, ...)
Input:
obj sw class object.
Options:
One of the following options has to be given in the input:
label Label of the matrix that is already assigned to either as
anisotropy or coupling only once.
mat_idx Index of the matrix, stored in obj.matrix. Alternative to
the 'label' option.
coupling_idx Value of the obj.coupling.idx, that defines the coupling,
for which the symmetry allowed matrix elements have to be
determined.
aniso_idx Value of the obj.matom.idx, that selects a magnetic atom,
for which the symmetry allowed anisotropy matrix elements
have to be determined.
g_idx Value of the obj.matom.idx, that selects a magnetic atom,
for which the symmetry allowed elemtns of the g-tensor
have to be determined.
Optional inputs:
tol Tolerance for printing the output for the smallest matrix
element.
pref Defines prefactors as a vector for the symmetry allowed
components, dimensions are [1 nSymMat]. Alternatively, if only
a few of the symmetry allowed matrices have non-zero
prefactors, use:
{[6 0.1 5 0.25]}
This means, the 6th symmetry allowed matrix have prefactor 0.1,
the 5th symmetry allowed matrix have prefactor 0.25. Since
Heisenberg isotropic couplings are always allowed, a cell with
a single element will create a Heisenberg coupling, example:
{0.1}
This is identical to obj.matrix.mat = eye(3)*0.1
For DM interactions (antisymmetric coupling matrices), use
three element vector in the cell:
{[D1 D2 D3]}
In this case, these will be the prefactors of the 3
antisymmetric symmetry allowed matrices. In case no crystal
symmetry is defined, these will define directly the components
of the DM interaction in the xyz coordinate system. Be
carefull with the sign of the DM interaction, it depends on the
order of the two interacting atoms! Default value is {1}.
For anisotropy matrices antisymmetric matrices are not allowed.
Output:
aMat If no prefactors are defined, aMat contains all symmetry
allowed elements of the coupling/anisotropy matrix, dimensions
are [3 3 nSymMat]. If prefactor is defined, it is a single 3x3
matrix, that is a sum of all symmetry allowed elemenets
multiplied by the given prefactors.
Example:
cryst = sw;
cryst.genlattice('sym','P 4')
cryst.addatom('r',[0 0 0],'label','MCu2')
cryst.addmatrix('label','A','value',eye(3))
cryst.gencoupling
cryst.addaniso('A')
cryst.getmatrix('label','A','fid',1);
The above example determines the allowed anisotropy matrix elements in
the C4 point group symmetry (the symmetry at the [0 0 0] atomic
position) and prints them onto the Command Window. The allowed matrix
elements are: diag([A A B]).
See also SW.SETMATRIX.