This method is formulated for large (> 100 atoms) nanoalloys of metals with small size mismatch such as those formed by gold and platinum . Local relaxation effects in such particles are small and involve a minimal loss of crystallinity, which allows constraining the optimization problem to changes in occupation of crystal lattice positions. The energies of bimetallic particles in the resulting space of conformations can be approximated by surrogate models based on e.g. bond-centric parameters or topological descriptors . These approaches significantly reduce the computational cost with respect to first principles approaches commonly used for such systems. The Hamiltonian for the topological descriptor model proposed by Kozlov et al. (analogous to a transverse field Ising model) is expressed as