Structures and Dynamics in Condensed Systems

Personnel

Project Leader(s):
Matthew Kramer

Principal Investigators:
Alan Goldman, Matthew Kramer, Mikhail Mendelev, Ralph Napolitano, Ryan Ott, Xueyu Song, Cai-Zhuang Wang,

Overview

This project concentrates on developing quantitative, self-consistent structural descriptions of liquid and amorphous states in metallic systems. Our research moves beyond static structural descriptions towards a detailed thermodynamic understanding of liquid and amorphous states, consistent with structural models. Binary alloys are emphasized to more accurately describe local structure. Moreover, the capabilities of the Materials Preparation Center are utilized to synthesize high-purity alloys having precise composition control. Experimental methods, atomistic simulations, and fundamental theoretical predictions are integrated for the measurement of structure, chemistry, and macroscopic thermodynamic properties in selected liquid and amorphous Al- and Zr-based model systems.

This project utilizes DOE-supported x-ray and neutron sources to capture structural- and chemically-specific details about short- and medium-range order in disordered systems. In addition, targeted scattering data are used to support efforts to develop highly accurate inter-atomic potentials. Simulation approaches include ab initio, constrained reverse Monte Carlo, and classical molecular dynamics using both pair-wise and, more importantly, many-body inter-atomic potentials, including tight-binding and embedded-atom method approaches. A new "embedded-cluster" method for ab initio calculations is pursued to mitigate the artifacts created by periodic boundary conditions of conventional first-principles methods. Combined with experimental data, simulations ultimately allow us to predict—e.g., changes in temperature, strain, or composition—alterations in local and long-range atomic ordering, leading to different disordered structures or perhaps highly-correlated phase transformations.

Highlights

Publications