On the classical r -matrix structure of the rational BCnBCn Ruijsenaars–Schneider–van Diejen system

In this paper, we construct a quadratic r  -matrix structure for the classical rational BCnBCn Ruijsenaars–Schneider–van Diejen system with the maximal number of three independent coupling parameters. As a byproduct, we provide a Lax representation of the dynamics as well.