Energetic and magnetic properties of chitosan with embedded Co clusters

Ab initio DFT simulations of cobalt clusters adsorbed on polymer chitosan molecules with increasing size of both Co clusters and polymer molecules are reported. Small cobalt clusters (CoN, N = 2–19 atoms) in the ground state are bound to polymer chitosan molecules containing up to four monomers. The different kinds of binding for Co clusters to chitosan were taken in special attention, such as inside and outside connection. It is shown that O- and N-binding types are competitive for outside linking. Co nanoparticles embedded into the internal part of chitosan helix lose greater energy as compared with outside binding. The size of not only Co clusters, but also the chitosan polymer molecules is significant during the simulation. Magnetic moments of the Co–chitosan system depend strongly on the size of neither Co clusters nor chitosan molecules and tend to be slightly decreased in the case of inside connected clusters with increasing the system’s size.