In the present Letter, large ternary hydrogen-bonded (H2SO4)(n)(NH3)(m)(H2O)(k) clusters have been studied using the Density Functional Theory (DFT). Binary and ternary (H2SO4)(n)(NH3)(m)(H2O)(k) clusters have been studied focusing on thermochemical properties, which are relevant directly to atmospheric nucleation rates and controlled by affinities of H2SO4, NH3 and H2O to the aforementioned pre-nucleation clusters. The composition and size dependencies of the affinities have been studied and structure-properties correlations have been discussed. New thermochemical data for large binary and ternary clusters reported in the present study are ready to be used in the development of quantum-constrained parameterization of ternary nucleation rates. (C) 2011 Elsevier B.V. All rights reserved.