Perturbation methods for the matrix eigenproblem
John P. Killingbeck, Georges Jolicard · Journal of Physics A Mathematical and General · 1992
Some computational experiments are reported on the solution of the eigenproblem for a matrix H by using an iterative sequence of transformations of type H to S -1 HS, where S is trivially invertible and is usually calculated from a first-order perturbation formula. Simple improved methods of constructing S are reported; these methods greatly improve the convergence properties of the eigenvalue calculations.