# FESSDE, a program for the finite-element solution of the coupled-channel Schrödinger equation using high-order accuracy approximations

## Description

Abstract A FORTRAN 77 program is presented which solves the Sturm-Liouville problem for a system of coupled second-order differential equations by the finite element method using high-order accuracy approximations. The analytical and tabular forms of giving the coefficients of differential equations are considered. Zero-value (Dirichlet) and zero-gradient (Neumann) boundary conditions are also considered. Title of program: FESSDE Catalogue Id: ACVU_v1_0 Nature of problem Coupled second-order differential equations of the form <PRE> d dY(x) - -- [P(x)-----] + [U(x) - lambdaR(x)]Y(x) = 0, x contained in [a,b], dx dx with boundary conditions dY(x)| Y(a) = 0 or -----| = 0, dx |x=a dY(x)| Y(b) = 0 or -----| = 0, dx |x=b </PRE> are solved. Here lambda is an eigenvalue, Y(x) is an eigenvector, P(x), U(x) and R(x) are symmetrical matrices, P(x) is a diagonal matrix, elements of which are the differentiable functions on a given interval [a,b], and R(x) is a positive matr ... Versions of this program held in the CPC repository in Mendeley Data ACVU_v1_0; FESSDE; 10.1016/0010-4655(94)00107-D ACVU_v2_0; FESSDE 2.2; 10.1016/S0010-4655(98)00099-X This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)