With the advent of X-ray diffraction and crystal structure determination in 1912 researchers in physics and chemistry began investigating the problem of crystal co hesion, i. e. , on the question of what holds crystals together. The names of M. Born, E. Madelung, P. P. Ewald, F. Bloch, E. P. Wigner, and J. E. Mayer are, in particular, associated with the pre-1940 work on the cohesion of inorganic lattices. The advent of digital computers brought along great advances in the detailed understanding of ionic crystals, molecular crystals, and metals. The work of P. O. Lowdin and r A. I. Kitaigorodosky are seminal i these more recent advances. This volume is a collection of specialist reports on a subset of the general problem of crystal cohesion. It is intended for researchers and advanced students in solid-state chemistry and physics, and biochemistry. WILLIAMS reports on the mole cule-independent empirical parameters for dispersion and repulsion that explain, and can predict, the cohesive energy of neutral organic lattices. MOMANY applies similar procedures to the conformational energy problem and shows how they can be used for the pharmacological problems of polypeptide drug design. METZGER uses quantum-mechanical molecule-dependent atom-in-molecule charges, dipole moments, and polarizabilities to study the cohesion of organic ionic (semiconducting) and par tially ionic (metallic) lattices. SILVERMAN emphasizes, with quantum-mechanical dimer calculations, the importance of dispersive interactions for the observed stacking modes in organic metallic lattices.

Inhalt

1. Introduction.- References.- 2. Transferable Empirical Nonbonded Potential Functions.- 2.1 Introductory Comments.- 2.2 Empirical Nonbonded Potential Models.- 2.3 Nonbonded Interactions in Molecular Crystals.- 2.4 Accelerated Convergence of Lattice Sums.- 2.5 Derivation of Nonbonded Potential Parameters.- 2.6 Extensions of the Potential Model.- 2.7 Appendix. Derivatives of C.- References.- 3. Conformational Analysis and Polypeptide Drug Design.- 3.1 Introductory Comments.- 3.2 Computational Procedures.- 3.3 Polypeptides and Their Constituents.- 3.4 Application of Conformational Information to Drug Design.- 3.5 Conclusions.- References.- 4. Cohesion and Ionicity in Organic Semiconductors and Metals.- 4.1 Introductory Comments.- 4.2 Crystal Cohesive Energies: General Theory.- 4.3 Born-Haber Cycles and Criteria for Ionicity.- 4.4 Lattice Energy Calculations.- References.- 5. Slipped Versus Eclipsed Stacking of Tetrathiafulvalene (TTF) and Tetracyanoquinodimethane (TCNQ) Dimers.- 5.1 Introductory Comments.- 5.2 Geometry of Donor-Acceptor ? Complexes: Slipped Versus Eclipsed Stacking.- 5.3 Molecular-Orbital Calculations.- 5.4 Interactions Between Closed-Shell Neutral TTF Molecules: Hard-Sphere Packing and Atom-Atom Potentials in Crystalline TTF.- 5.5 Density-Functional Calculation: Neutral TTF Dimer.- 5.6 Density-Functional Calculation: Open Shell TTF Dimer.- 5.7 Conclusions.- References.