| 英文摘要: | Broader implications.
Understanding chemical processes (what happens to molecules and atoms) on mineral and other solid surfaces is a critical part of the science underlying how minerals behave throughout nature. The science of such surfaces also has implications for industrially important processes involving solid surfaces, such as the catalysis used for plastics manufacturing. Scientists have found that in order to understand what happens on surfaces at the molecular scale, computational modeling of these processes is absolutely essential. This work focuses on advancing modeling of mineral surfaces, which is important for both geochemistry and chemistry. Currently, the theories and models used to simulate interactions between atoms and molecules exhibit a large range in both the quality of results and the kinds of problems that can be addressed. There is a great need for models that are mathematically simple enough to be applied to large systems of atoms, but that are capable of greater accuracy and transferability. The research team will work on creating such a model by expanding a simple bonding model commonly used by crystallographers, the Bond-Valence Model, in a manner that is easily applied to atomistic simulations.
An additional component of this award entails building a future US STEM workforce that is capable not only in geoscience, but also in computer programming, modeling, and data analysis. In geoscience (as well as all fields of STEM), both in industry and academia, the ability to comfortably use computing is growing in its importance. Traditionally, geoscience degree programs do not require students to acquire significant computer programming and data analysis skills. This project will require undergraduate researchers to do data mining, exploratory data analysis, and optimization, using the MATLAB scientific programming environment. Training in these skills will be provided to the students by the principal investigator.
This project has implications for science beyond geochemistry, and, as such, is being jointly funded by the Environmental Chemical Sciences program (NSF Division of Chemistry) and the cross-disciplinary NSF Computational and Data-Enabled Science and Engineering program.
Technical description.
In this project, principal investigator Barry Bickmore and his group will continue work to create a simplified chemical bonding model, based on the bond-valence model (BVM), that can be easily transferred to a molecular mechanics framework for atomistic simulations. The potential energy terms in this model are primarily based on multipole (monopole, dipole, and quadrupole) expansions of bond valences about each atom. These terms tend to be surprisingly predictable, and describe all major aspects of molecular structure, including distortions due to electronic structure effects (lone-pair and Jahn-Teller). They are also intrinsically multi-body terms that describe aspects of the total bonding environment about each atom, rather than focusing on individual atom pairs. This allows for very complex interactions to be modeled using a small number of parameters. The present work focuses on developing the bonding model to predict ideal values of the BVM-based structural descriptors, as well as energy cost functions for deviations from the ideal values. In addition, we are developing some preliminary molecular mechanics force fields to further test the concept. A number of undergraduate researchers will be involved in the project, and will learn computer programming, data analysis, and optimization techniques. |