A well known property of anM-matrixA is that the inverse is element-wise non-negative, which we write asA−1 0. In this paper we consider perturbations ofM-matrices and obtain bounds on the perturbations so that the non-negative inverse persists. The bounds are written in terms of decay estimates which characterize the decay (along rows) of the elements of the inverse matrix. We obtain results f...

This paper is a continuation of the previous one [Journal xx, xxxxx (2022)]. Here, we reformulate same J-matrix theory by regularizing inverse square singular potential. The objective to restore rapid convergence calculation in and recover conventional tridiagonal representation. Partial success achieved.

We present partitioned (blocked) algorithms for reducing a symmetric matrix to a tridiagonal form, with partial pivoting. That is, the algorithms compute a factorization PAP = LTL where P is a permutation matrix, L is lower triangular with a unit diagonal, and T is symmetric and tridiagonal. The algorithms are based on the column-by-column methods of Parlett and Reid and of Aasen. Our implement...

A method for the inversion of block tridiagonal matrices encountered in electronic structure calculations is developed, with the goal of efficiently determining the matrices involved in the Fisher–Lee relation for the calculation of electron transmission coefficients. The new method leads to faster transmission calculations compared to traditional methods, as well as freedom in choosing alterna...

We study the Bethe ansatz equations for a generalized XXZ model on a one-dimensional lattice. Assuming the string conjecture we propose an integer version for vacancy numbers and prove a combinatorial completeness of Bethe's states for a generalized XXZ model. We nd an exact form for inverse matrix related with vacancy numbers and compute its determinant. This inverse matrix has a tridiagonal f...

In this paper two fast algorithms that use orthogonal similarity transformations to convert a symmetric rationally generated Toeplitz matrix to tridiagonal form are developed, as a means of finding the eigenvalues of the matrix efficiently. The reduction algorithms achieve cost efficiency by exploiting the rank structure of the input Toeplitz matrix. The proposed algorithms differ in the choice...

Numerical quantum transport calculations are commonly based on a tight-binding formulation. A wide class of quantum transport algorithms requires the tight-binding Hamiltonian to be in the form of a block-tridiagonal matrix. Here, we develop a matrix reordering algorithm based on graph partitioning techniques that yields the optimal block-tridiagonal form for quantum transport. The reordered Ha...

A method for the inversion of block tridiagonal matrices encountered in electronic structure calculations is developed, with the goal of efficiently determining the matrices involved in the Fisher–Lee relation for the calculation of electron transmission coefficients. The new method leads to faster transmission calculations compared to traditional methods, as well as freedom in choosing alterna...

A simple and efficient numerical algorithm for computing the exponential of a symmetric matrix is developed in this paper. For an n× n matrix, the required number of operations is around 10/3 n. It is based on the orthogonal reduction to a tridiagonal form and the Chebyshev uniform approximation of e−x on [0,∞).

To solve the non-relativistic time dependent Schrödinger equation using the Lanczos method, Park and Light have provided an approximate expression for the time step for a given accuracy. We provide an exact expression for the time step in terms of the eigenvalues and eigenvectors of the resulting tridiagonal matrix. For two test problems, the values of the time step provided by Park and Light d...