Accurate computation of individual and tables of \(3\)-\(j\) and \(6\)-\(j\) symbols (Q1299673)

The authors present techniques to rewrite the formulas for Wigner \(3\)-\(j\) and \(6\)-\(j\) symbols in terms of several alternating binomial sums. Three methods are investigated: direct summation, center recursion and edge recursion. The accuracy of single and double precision 3-\(j\) binomial formulas is discussed for all methods. As a result quick and accurate calculations of \(3\)-\(j\) and \(6\)-\(j\) symbols are performed and \(9\)-\(j\) calculations are in progress. Standard Fortran 77 subroutines for \(3\)-\(j\) and \(6\)-\(j\) symbols using floating point binomial sum direct summation or recursion are available from the authors. Applications are expected in molecular physics and chemistry, in spectroscopy, scattering and other connected areas.