Grinding-induced homochirality in crystal growth

When two enantiomeric chiral crystals are ground in the solution, one enantiomer dominates the other and eventually homochirality is accomplished. To elucidate this homochirality in crystal growth, we performed kinetic Monte Carlo (KMC) simulations of two models; an ARS model where achiral monomer A crystallizes in R or S type crystal clusters, and a RS model where chiral molecules R and S convert their chirality in a monomer state prior to the formation of conglomerate. KMC simulation of both models reproduces chiral symmetry breaking when crystal is grown under grinding. Time-evolution of the number densities of R and S molecules is well-explained by rate equations with antagonistic and cooperative nonlinear terms.