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Iowa State University

Elementary Particles and Fields and String Theory

Ames Laboratory Accepted Manuscripts

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Full-Text Articles in Physics

Discontinuous Phase Transitions In Nonlocal Schloegl Models For Autocatalysis: Loss And Reemergence Of A Nonequilibrium Gibbs Phase Rule, Da-Jiang Liu, Chi-Jen Wang, James W. Evans Sep 2018

Discontinuous Phase Transitions In Nonlocal Schloegl Models For Autocatalysis: Loss And Reemergence Of A Nonequilibrium Gibbs Phase Rule, Da-Jiang Liu, Chi-Jen Wang, James W. Evans

Ames Laboratory Accepted Manuscripts

We consider Schloegl models (or contact processes) where particles on a square grid annihilate at a rate p and are created at a rate of kn=n(n−1)/[N(N−1)] at empty sites with n particles in a neighborhood ΩN of size N. Simulation reveals a discontinuous transition between populated and vacuum states, but equistable p=peq determined by the stationarity of planar interfaces between these states depends on the interface orientation and on ΩN. The behavior for large ΩN follows from continuum equations. These also depend on the interface orientation and on ΩN shape, but a unique ...


Electronic, Magnetic, And Magnetocrystalline Anisotropy Properties Of Light Lanthanides, T. A. Hackett, D. J. Baldwin, Durga Paudyal Nov 2017

Electronic, Magnetic, And Magnetocrystalline Anisotropy Properties Of Light Lanthanides, T. A. Hackett, D. J. Baldwin, Durga Paudyal

Ames Laboratory Accepted Manuscripts

Theoretical understanding of interactions between localized and mobile electrons and the crystal environment in light lanthanides is important because of their key role in much needed magnetic anisotropy in permanent magnet materials that have a great impact in automobile and wind turbine applications. We report electronic, magnetic, and magnetocrystalline properties of these basic light lanthanide elements studied from advanced density functional theory (DFT) calculations. We find that the inclusion of onsite 4f electron correlation and spin orbit coupling within the full-potential band structure is needed to understand the unique magnetocrystalline properties of these light lanthanides. The onsite electron correlation, spin ...


Oscillatory Electrostatic Potential On Graphene Induced By Group Iv Element Decoration, Chunyan Du, Liwei Yu, Xiaojie Liu, Lili Liu, Cai-Zhuang Wang Jan 2017

Oscillatory Electrostatic Potential On Graphene Induced By Group Iv Element Decoration, Chunyan Du, Liwei Yu, Xiaojie Liu, Lili Liu, Cai-Zhuang Wang

Ames Laboratory Accepted Manuscripts

The structures and electronic properties of partial C, Si and Ge decorated graphene were investigated by first-principles calculations. The calculations show that the interaction between graphene and the decoration patches is weak and the semiconductor patches act as agents for weak electron doping without much disturbing graphene electronic π-bands. Redistribution of electrons due to the partial decoration causes the electrostatic potential lower in the decorated graphene areas, thus induced an electric field across the boundary between the decorated and non-decorated domains. Such an alternating electric field can change normal stochastic adatom diffusion to biased diffusion, leading to selective mass transport.