The interaction of two peptide monomers with each mica surface was simulated, the secondary structure of the monomers is characterized using the defined secondary structure of proteins (DSSP) method25 (Fig. 4B). In the Mica1 system, Aβ(14-23) monomer A rapidly interacts with the mica surface; within the first 50 ns of the simulation the monomer approaches the surface. Binding of the monomer is accompanied by its structural transformation, going from having a small helical segment to assuming a bend structure, as seen with the change in secondary structure in Fig. 4B. The interaction between the monomers was characterized by the distance between them as a function of time as shown in Fig. 4C and D. A few snapshots illustrating the peptide structure are indicated along the time trajectory. The surface induces a conformation that is favorable for dimer formation, as is evident from the rapid recruitment of the free monomer and the formation of a dimer bound to the surface, Fig. 4D. Recruitment of the free monomer, monomer B, happens within the first 100 ns of the simulation; the dimerization causes a structural change in the previously free monomer, Fig 4B. However, the newly formed dimer is only formed transiently and for the next ~200 ns forms and dissociates multiple times as is demonstrated by the fluctuation of the dimer-surface plot in Fig 4C. The dimers interact with the surface primarily staying in contact with the surface through interactions involving a few residues and rarely lie fully on the surface. The behavior of the Aβ(14-23) monomers in the Mica2 system is very similar to the Mica1 system, with the exception that the interaction of peptides with the surface is not as strong, and the conformation of the dimers formed is less compact, Supplementary Fig. 8.