Two-particle-shift Monte-Carlo method for simulating the composition of solvated complexes

We propose a modified Monte-Carlo method for studying the solvation of ions in a mixed solvent. We include two-particle shifts in the algorithm along with oneparticle shifts. Some of the two-particle shifts end with exchange of adjacent molecules. We have carried out calculations for the system Na+-N1·H2O-N2·MeOH for N1=N2=6 and N1=N2=9. We have concluded that there is preferential hydration of the Na+ ion in an equimolar water-methanol mixture.