The atom–atom approximation and the lattice energies of 2,2'-bis-1,3-dithiole (TTF), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and their 1:1 complex (TTF–TCNQ)

Abstract

The van der Waals and repulsive contributions to the lattice energies of TTF (C₆H₄S₄), TCNQ (C₁₂H₄N₄) and TTF-TCNQ (C₆H₄S₄.C₁₂H₄N₄) at room temperature were calculated by the atom-atom approximation. In addition the Madelung electrostatic contributions were calculated by Ewald's method for TTF and TCNQ. The combined atom-atom and electrostatic contributions produced lattice energies in accordance with the experimental enthalpies of sublimation and dissociation within 0-5 kcal mol^-1.