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Density functional theory provides a first-principles approach for computing the geometric and electronic structures, and a wealth of corresponding properties, of a wide range of materials types and compositions, including bulk solids, surfaces, defects and clusters of molecules. Parallel advances in hardware performance, implementation strategies and algorithms have all contributed to a rapid growth in the number of important applications. Recent developments under each of these themes are outlined and the breadth of current applications is illustrated by typical examples. Issues associated with the implementation and performance of density functional methods on parallel computer architectures are discussed.

We study the structure and growth sequence of small palladium clusters Pdn using the Many-Body Alloy (MBA) potential and simulated annealing techniques. Our results show the preference of compact polyhedral structures. These equilibrium structures are compared with the bulk Pd crystal in terms of cohesive energies and nearest neighbor distances. Both the cohesive energy and the nearest neighbor distance show a slow convergence to bulk behaviors. By analyzing the detailed structures and cohesive energies, we find that Pd4, Pd7 and Pd13 are magic number structures, which are the consequence of their high symmetry and large coordination number.

We show that the frequencies of certain optically active lattice vibrational modes in a large number of zeolites can be used as direct structural probes. Mode frequencies are found to depend on the cosine of the T-O-T angle and the Si/Al ratio of the framework. The relationship between mode frequency and local framework structure is discussed in terms of a complete lattice dynamics calculation for specific zeolite structures as well as a lattice dynamical model of amorphous glasses.

In this paper we demonstrate the usefulness of a nearest neighbor force model for studying the structural dependence of the lattice dynamics of zeolites. Interpreting Raman scattering in the context of this model confirms earlier empirical vibrational assignments in zeolites and underlines the importance of short range forces in determining the frequencies of certain zeolite vibrational modes. The model describes fully the low frequency bond bending mode of A1 symmetry, although long range forces are shown to be required to model complete zeolite vibrational spectra.