The corresponding single excitation Hamiltonian matrix elements are then generally large and pivotal in the wave function optimization. Thus, the development of efficient sampling schemes for single excitations becomes particularly relevant for localized orbital bases. These orbital bases play a crucial role in our recently discovered compression of spin-adapted wave functions of ground and excited states of exchange coupled polynuclear transition metal clusters. Inspired and motivated by our research carried on localized orbital bases, we have developed a novel PCHB algorithm that, relying on locality of the correlation effects, has an increased excitation generation efficiency for both single and double excitations. This algorithm is the focus of this work.