Syntax
[m, asym] = sw_basismat(symop, r, tol)
Description
[m, asym] = sw_basismat(symop, r, tol) determines the allowed tensor
elements compatible with a given point group symmetry. The tensor can
describe exchange interaction or single ion anisotropy. The function
applies the symmetry invariance of the classical energy
\(\mathbf{S}_i\cdot \mathcal{M}\cdot \mathbf{S}_j\). Thus this symmetry
analysis includes the transformation properties of spin operators as
well.
Input Arguments
symOp- Generators of the point group symmetry, in a matrix with dimensions of
\([3\times 3\times n_{sym}]\) where each
symOp(:,:,ii)matrix defines a rotation. r- Distance column vector between the two interacting atoms. For anisotropy \(r=0\).
tol- Tolerance, optional, default value is \(10^{-5}\).
Output Arguments
M- Matrices, that span out the vector space of the symmetry allowed matrices, dimensions are \([3\times 3\times n_M]\). Any matrix is allowed that can be expressed as a linear combination of the symmetry allowed matrices.
asym- Logical vector, for each \([3\times 3]\) matrix in \(M\), tells whether it is antisymmetric stored in a row vector with \(n_M\) elements.