In this paper we propose an accurate, highly parallel algorithm for the
generalized eigendecomposition of a matrix pair (H,S), given in a factored
form (F∗JF,G∗G). Matrices H and S are generally complex
and Hermitian, and S is positive definite. This type of matrices emerges from
the representation of the Hamiltonian of a quantum mechanical system in terms
of an overcomplete set of basis functions. This expansion is part of a class of
models within the broad field of Density Functional Theory, which is considered
the golden standard in condensed matter physics. The overall algorithm consists
of four phases, the second and the fourth being optional, where the two last
phases are computation of the generalized hyperbolic SVD of a complex matrix
pair (F,G), according to a given matrix J defining the hyperbolic scalar
product. If J=I, then these two phases compute the GSVD in parallel very
accurately and efficiently.Comment: The supplementary material is available at
https://web.math.pmf.unizg.hr/mfbda/papers/sm-SISC.pdf due to its size. This
revised manuscript is currently being considered for publicatio