Аннотация:The geometry and energies of (CH3CN)n (n = 2–8) and (CH3CN)n-1·H2O (n = 3–7) clusters have been calculated by density functional theory method with functional B3LYP/cc-pvdz accounting the dispersive correction Grimme D3. In the structure of clusters (CH3CN)n at n ≤ 4 the anti-parallel arrangement of acetonitrile molecules is realized, at increasing n it is possible to distinguish cycles where molecules are oriented "head to tail". At the same n energetically more favorable formation of clusters that include a water molecule, and starting from n = 6 it is located inside the cavity of acetonitrile molecules
