Computational Analysis Using Normal and Multibody Modes


William A. Goddard IIIDepartment of Chemistry, California Institute of Technology

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The complexity of real materials with their intriguing interplay between chemical composition, atomic arrangements, microstructures, and macroscopic behavior makes computational modeling and materials design extremely difficult. Even with the fundamental laws of quantum mechanics and statistical physics, the availability of high-performance computers, and with the growing range of sophisticated software systems accessible to an increasing number of scientists and engineers, the goal of designing novel materials from first principles continues to elude most attempts. On the other hand, computational experiments have led to increased understanding of atomistic origins of molecular structure and dynamics. In particular, the molecular dynamics and mechanics methods have yielded a wealth of knowledge on the structural and dynamical behavior of various polymeric materials as a function of temperature and pressure.

For a number of years, computational scientists have been able to perform first principles quantum mechanical calculations on small systems, typically tens to hundreds of atoms and molecular dynamics simulations on larger systems composed of thousands of atoms. Calculations on larger systems, however, remain at the edge of tractability, due to memory, storage, and computation limits. These systems include a wide range of important applications, from biological applications such as protein modeling, to materials applications such as bulk properties of ceramics, metals, and polymers. Recently, there has been much effort to make theoretical predictions of nanoscale structures, both for use in mesoscale simulations and microscopic engineering design problems, and also for the pure intellectual challenge of working with these large molecular structures.