Lattice energy of ionic crystals

It is evident that the electrostatic interactions constitute a major component of the lattice energy of ionic crystals. According the treatment for NaF described above, the ratio of absolute values of the electrostatic and repulsive forces to the lattice energy is l l/n, where n is the Born coefficient. With n ff = 7.445 (Table... 

Trends in Lattice Energy. We have seen that the lattice energy of ionic crystals is affected to some extent by the coordination numbers of the ions (Table 3.4) and by repulsion between ions in contact with each other (Eq. 3.14). These factors are, however, of minor importance when compared to the effect of ionic charge and ionic size. 

Kapustinskii, A. F. Lattice Energies of Ionic Crystals, Quart. Revs., X, 283 (1956). 

A brief account will be given in this Section of the various methods that have been employed to calculate the lattice energies of ionic crystals, starting with a discussion of the extended classical calculation. Each term in this calculation will be discussed separately. 

Plots of lattice energy of ionic crystals AX against radius ratio show that the cubic ZnS structure becomes more stable than the NaCl structure only at values of x than about 0-35 rather than 0-41.) Of the salts with radius ratio greater than 0-732 only CsCl, CsBr, and Csl normally adopt the 8-coordinated CsCl structure. We find the same persistence of the NaCl structure in monoxides, where the CsCl structure might have been expected for SrO, BaO, and PbO in fact there is no monoxide with the CsCl structure. The c.n. six is not exceeded although the pairs of ions K and F, Ba and 0 , have practically the same radius. 

The interaction energies of dissolved ions with the surrounding solvent are large, comparable to the lattice energies of ionic crystals. Changes in these ion-solvent interactions on transfer of electrolytes between solvents are smaller, but are... 

An alternative to truncation of any kind is the use of Ewald Sums, as originally introduced to calculate the lattice energy of ionic crystals. A fast algorithm, "Particle Mesh Ewald (PME)" (23), has recently been devised which makes this approach viable in full-scale MD on macromolecules in solvent. The initial round of PME simulations on DNA demonstrated a higher degree of stability and less deviation from the starting structure (24, 25). The accuracy of the... 

Kapustinskii AF (1956) Lattice energy of ionic crystals. Quart Rev Chem Soc 10 283-294 Kariuki BM, Serrano-Gonzalez H, Johnston RL, Harris KDM (1997) The apphcation of a genetic algorithm for solving crystal structures from powder diffraction data. Chem Phys Lett 280 189-195 Kleimnan DA, Spitzer WG (1962) Phys Rev 125 16... 

Kapustinskii A (1933) On the second principle of crystal chemistry. Z Krist 86 359—369 Kapustinskii A (1943) Lattice energy of ionic crystals. Acta Physicochim URSS 18 370-377 261. Yatsimirskii KB (1951) Thermochemistry of coordination compounds. Akad Nauk, Moscow (in Russian)... 

A. F. Kapustinskii, Lattice energy of ionic crystals. Quart. Rev. Chem. Soc. 1956, 10, 283. 

In contrast, truncation at a computationally feasible (i.e., small) value of R. produces artifacts when the system is strongly ionic because the potential energy is dominated by the slowly varying 1/r terms.To address this, a popular approach known as Ewald or lattice sum (similar to the one used to calculate the lattice energy of ionic crystals) is used to sum the electrostatic interactions in the simulation box and all of its replicas. This is done by rewriting the sum of the 1/r terms as a sum of a rapidly converged series in real space (so a small cutoff can be used for these terms) and a much more slowly varying smooth function that can be approximated by a few cosine and sine terms in reciprocal (k) space.These are expensive calculations that scale like... 

The lattice energy of ionic crystals is defined as the negative reaction energy of... 

Energy Changes in the Formation of Ionic Crystals— Lattice energies of ionic crystals can be related to certain atomic and thermodynamic properties by means of the Born-Fajans-Haber cycle (Fig. 12-51). 

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