# Exact computation of the 9-j symbols

## Description

Abstract A useful algebraic for the 9-j symbol has been written for inconvinient use on a computer. A simple FORTRAN program for the exact computation of 9-j symbols has been written for the VAX with VMS version V5.4-1 according to this formula. The results agree with the approximate values in existing literature. Some specific values of 9-j symbols needed for the intensity and alignments of three-photon nonresonant transitions are tabulated. Approximate 9-j symbol values beyond the limitation of the ... Title of program: W9J Catalogue Id: ACHW_v1_0 Nature of problem The program calculates the exact 9-j (for low angular momentum j up to j=10) and the approximate 9-j coefficient (for high j up to j=90 or higher), using the triple sum formula due to Jucys and Bandzaitis (rewritten for exact computational use by authors). This coefficient arises in the recoupling of four angular momenta, which can be coupled by different schemes. It is of fundamental importance in the evaluation of matrix elements in nuclear, atomic, molecular physics and molecular reaction dyn ... Versions of this program held in the CPC repository in Mendeley Data ACHW_v1_0; W9J; 10.1016/0010-4655(92)90115-F This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)