期刊
HIGH ENERGY DENSITY PHYSICS
卷 5, 期 1-2, 页码 44-50出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.hedp.2009.02.001
关键词
EXAFS; Shock; Molecular dynamics
资金
- Daresbury Laboratory through North West Science Initiative
- AWE, Aldermaston
- European Union
- National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory [DE-AC52-06NA25396]
- ASC
- [LDRD-20050107 DR]
Simulated EXAFS signals from ab initio models and configurational averaging of molecular dynamics (MD) data are compared for alpha-Fe, and configurationally averaged MD EXAFS signals are compared with experimental data for iron shock compressed to pressures above the alpha-epsilon transition pressure. It is shown that molecular dynamics potentials and ab initio models capable of recreating similar vibrational density of states lead to EXAFS signals in good mutual agreement. The effects of the classical nature of the phonon distribution in the MD and the anharmonicity of the potential give rise to noticeable differences between ab initio models and configurational averaging of MD data. However, the greatest influence on the spectra is the form of the potential itself. We discuss the importance of these effects in simulating EXAFS spectra for shock compressed polycrystalline iron. It is shown that EXAFS is an insensitive probe for determining the nature of the close packed product phase in this system. (C) 2009 Elsevier B.V. All rights reserved.
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