Phase Equilibria in the U-Si System from First-Principles Calculations

Abstract

Density functional theory calculations have been used with spin-orbit coupling and on-site Coulomb correction (GGA + U) methods to investigate the U-Si system. Structural prediction methods were employed to identify alternate stable structures. Convex hulls of the U-Si system were constructed for each of the methods to highlight the competing energetics of various phases. For GGA calculations, new structures are predicted to be dynamically stable, but these have not been experimentally observed. When the GGA + U (Ueff > 1.3 eV) method is considered, the experimentally observed structures are predicted to be energetically preferred. Phonon calculations were used to investigate the energy predictions and showed that the use of the GGA + U method removes the significant imaginary frequencies observed for U3Si2 when the correction is not considered. Total and partial electron density of states calculations were also performed to understand the role of GGA + U methods and orbitals on the bonding and stability of U-Si compounds.

Department(s)

Physics

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Chemical Bonds; Density Functional Theory; Phase Equilibria; Semiconducting Silicon Compounds; Silicon; Bonding and Stability; Coulomb Corrections; Energy Prediction; First-Principles Calculation; Imaginary Frequency; Phonon Calculation; Prediction Methods; Spin-Orbit Couplings; Calculations

International Standard Serial Number (ISSN)

0022-3115

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Elsevier, All rights reserved.

Publication Date

01 Oct 2016

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