# Parallel computation of recoupling coefficients using transputers

## Description

Abstract Parallel algorithms for the computation of angular momentum recoupling coefficients are discussed. The first situation where parallelisation has a remarkable impact is for the computation of the 9-j coefficient. A parallel program in C for the numerical calculation of the 9-j coefficient is presented and compared with sequential programs in C. Title of program: NINEJPAR Catalogue Id: ACJE_v1_0 Nature of problem A parallel program calculates the 9-j coefficient (also called the ls-jj transformation coefficient) using the single sum over the product of three 6-j coefficients formula. This coefficient arises in the recoupl- ing of four angular momenta, which can be coupled either using the Russell-Saunders scheme or the jj-coupling scheme. It is of fundamental importance in the evaluation of matrix elements which occur in nuclear, atomic and molecular physics. Versions of this program held in the CPC repository in Mendeley Data ACJE_v1_0; NINEJPAR; 10.1016/0010-4655(92)90015-Q This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)