The probabilistic estimation of triplet invariants: the formulaP13
Maria Cristina Burla, Carmelo Giacovazzo, Anna Moliterni, Javier González‐Platas · Acta Crystallographica Section A Foundations of Crystallography · 1994
The second representation of a triplet invariant [Giacovazzo (1977). Acta Cryst. A33, 933–944] is a collection of special quintets. In the present paper, the triplet is embedded in many more additional quintets obtained in a special way by symmetry operations on the indices of the structure factors. The method of joint probability distribution functions has been used to derive a formula for estimating triplets via the information contained in the basis and in the cross terms of the quintet invariants. The P10 formula [Cascarano, Giacovazzo, Camalli, Spagna, Burla, Nunzi & Polidori (1984). Acta Cryst. A40, 278–283] is a special case of the new formula, here called P13. The new expression has been applied to practical cases.