Robust Quantum-Based Interatomic Potentials for Multiscale Modeling in Transition Metals
- PDF / 255,972 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 73 Downloads / 169 Views
EE4.7.1
Robust Quantum-Based Interatomic Potentials for Multiscale Modeling in Transition Metals John A. Moriarty, Lorin X. Benedict, James N. Glosli, Randolph Q. Hood, Daniel A. Orlikowski, Mehul V. Patel, Per Söderlind, Frederick H. Streitz, Meijie Tang and Lin H. Yang Lawrence Livermore National Laboratory, University of California Livermore, CA 94551-0808, U.S.A. ABSTRACT First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in transition metals and alloys within density-functional quantum mechanics. In central bcc transition metals, where multi-ion angular forces are important to structural properties, simplified model GPT or MGPT potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect and mechanical properties at both ambient and extreme conditions. Selected applications to multiscale modeling discussed here include dislocation core structure and mobility, atomistically informed dislocation dynamics simulations of plasticity, and thermoelasticity and high-pressure strength modeling. Recent algorithm improvements have provided a more general matrix representation of MGPT beyond canonical bands, allowing improved accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed for dynamic simulations, and the still-in-progress development of temperature-dependent potentials.
INTRODUCTION The prospect of modeling across length scales all the way from the atomic to the continuum level to achieve a predictive multiscale description of mechanical properties such as plasticity and strength has attracted widespread research interest in the last decade [1]. One of the most fundamental and important problems in such multiscale modeling is that of bridging the gap between first-principles quantum mechanics, from which true predictive power for real materials emanates, and the large-scale atomistic simulation of thousands or millions of atoms, which is usually essential to describe the complex atomic processes that link to higher length and time scales. For example, to model single-crystal plasticity at micron length scales via dislocation-dynamics (DD) simulations that evolve the detailed dislocation microstructure requires accurate largescale atomistic information on the mobility and interaction of individual dislocations. As indicated in Fig. 1, there currently exists a wide spectrum of atomic-scale simulation methods in condensed-matter and materials physics, extending from essentially exact quantum-mechanical techniques to classical descriptions with totally empirical force laws. All of these methods fall into one of two distinct categories, which are separated by a material-dependent gap. On one side of this gap are electronic methods based on direct
EE4.7.2
Material-
Data Loading...
