Algebraic reductions of the real symmetric 4 × 4 secular problem
Jan Linderberg · International Journal of Quantum Chemistry · 1981
Abstract Procedures for the construction of the eigenvector matrix and the spectrum of 4 × 4 real and symmetric matrices are given. The Lie algebra of the group O(4)† is used as well as the relation to O(3)†. Perturbations are analyzed in terms of the group parameters.