Irreducible Cartesian tensors (ICTs) are important in the design of equivariant graph neural networks and theoretical chemistry.
The ICT decomposition and basis for equivariant spaces are challenging to obtain for high-order tensors.
Researchers have achieved an explicit ICT decomposition for $n=5$ with factorial complexity and obtained decomposition matrices for ICTs up to rank $n=9$ with reduced complexity.
They used path matrices obtained through chain-like contraction with Clebsch-Gordan matrices to establish an orthonormal change-of-basis matrix and a complete orthogonal basis for the equivariant space.