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Title: First-principles calculation of principal Hugoniot and K-shell X-ray absorption spectra for warm dense KCl

Abstract

Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are calculated using the first-principles molecular dynamics (FPMD) method. Evolution of electronic structures as well as the influence of the approximate description of ionization on pressure (caused by the underestimation of the energy gap between conduction bands and valence bands) in the first-principles method are illustrated by the calculation. It is shown that approximate description of ionization in FPMD has small influence on Hugoniot pressure due to mutual compensation of electronic kinetic pressure and virial pressure. The calculation of X-ray absorption spectra shows that the band gap of KCl persists after the pressure ionization of the 3p electrons of Cl and K taking place at lower energy, which provides a detailed understanding to the evolution of electronic structures of warm dense matter.

Authors:
; ;  [1];  [2];  [3];  [1];  [2];  [1];  [2];  [2]
  1. HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)
  2. (China)
  3. Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
Publication Date:
OSTI Identifier:
22490935
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABSORPTION SPECTRA; ELECTRONS; ENERGY GAP; K SHELL; MOLECULAR DYNAMICS METHOD; P STATES; POTASSIUM CHLORIDES; VALENCE; X-RAY SPECTRA

Citation Formats

Zhao, Shijun, Zhang, Shen, Kang, Wei, E-mail: weikang@pku.edu.cn, College of Engineering, Peking University, Beijing 100871, Li, Zi, Zhang, Ping, Institute of Applied Physics and Computational Mathematics, Beijing 100088, He, Xian-Tu, E-mail: xthe@iapcm.ac.cn, College of Engineering, Peking University, Beijing 100871, and Institute of Applied Physics and Computational Mathematics, Beijing 100088. First-principles calculation of principal Hugoniot and K-shell X-ray absorption spectra for warm dense KCl. United States: N. p., 2015. Web. doi:10.1063/1.4922672.
Zhao, Shijun, Zhang, Shen, Kang, Wei, E-mail: weikang@pku.edu.cn, College of Engineering, Peking University, Beijing 100871, Li, Zi, Zhang, Ping, Institute of Applied Physics and Computational Mathematics, Beijing 100088, He, Xian-Tu, E-mail: xthe@iapcm.ac.cn, College of Engineering, Peking University, Beijing 100871, & Institute of Applied Physics and Computational Mathematics, Beijing 100088. First-principles calculation of principal Hugoniot and K-shell X-ray absorption spectra for warm dense KCl. United States. doi:10.1063/1.4922672.
Zhao, Shijun, Zhang, Shen, Kang, Wei, E-mail: weikang@pku.edu.cn, College of Engineering, Peking University, Beijing 100871, Li, Zi, Zhang, Ping, Institute of Applied Physics and Computational Mathematics, Beijing 100088, He, Xian-Tu, E-mail: xthe@iapcm.ac.cn, College of Engineering, Peking University, Beijing 100871, and Institute of Applied Physics and Computational Mathematics, Beijing 100088. Mon . "First-principles calculation of principal Hugoniot and K-shell X-ray absorption spectra for warm dense KCl". United States. doi:10.1063/1.4922672.
@article{osti_22490935,
title = {First-principles calculation of principal Hugoniot and K-shell X-ray absorption spectra for warm dense KCl},
author = {Zhao, Shijun and Zhang, Shen and Kang, Wei, E-mail: weikang@pku.edu.cn and College of Engineering, Peking University, Beijing 100871 and Li, Zi and Zhang, Ping and Institute of Applied Physics and Computational Mathematics, Beijing 100088 and He, Xian-Tu, E-mail: xthe@iapcm.ac.cn and College of Engineering, Peking University, Beijing 100871 and Institute of Applied Physics and Computational Mathematics, Beijing 100088},
abstractNote = {Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are calculated using the first-principles molecular dynamics (FPMD) method. Evolution of electronic structures as well as the influence of the approximate description of ionization on pressure (caused by the underestimation of the energy gap between conduction bands and valence bands) in the first-principles method are illustrated by the calculation. It is shown that approximate description of ionization in FPMD has small influence on Hugoniot pressure due to mutual compensation of electronic kinetic pressure and virial pressure. The calculation of X-ray absorption spectra shows that the band gap of KCl persists after the pressure ionization of the 3p electrons of Cl and K taking place at lower energy, which provides a detailed understanding to the evolution of electronic structures of warm dense matter.},
doi = {10.1063/1.4922672},
journal = {Physics of Plasmas},
number = 6,
volume = 22,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}
  • X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N{sub 2} molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electronmore » density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.« less
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  • The electrical and optical properties of warm dense beryllium along the principal Hugoniot for temperatures from 0.95 eV to 10.65 eV and densities from 3.8 to 6.0 g/cm{sup 3} are investigated by using quantum molecular dynamics (QMD) simulations combined with the Kubo-Greenwood formulation. The dc conductivity σ{sub dc} and the ionization fraction are yielded by fitting the optical conductivity with the Drude-Smith model. The first-principles transport coefficients are compared with results of the Lee-More model and the Brysk model [Plasma Phys. 17, 473 (1975)]. Compared with the QMD result, the Lee-More model underestimates σ{sub dc} by 87% at low temperatures, approaches the QMDmore » result gradually with the temperature rising, yet still underestimates σ{sub dc} by 49% corresponding to the temperature 10.65 eV. In the whole temperature range under investigation, the Brysk model overestimates the electronic thermal conductivity κ while the Lee-More model underestimates κ. The differences are reduced with the temperature increasing. At the temperature 10.65 eV, the Brysk κ is still around twice as large as the QMD result, and the Lee-More κ is smaller than the QMD data by about 40%. In addition, QMD Rosseland mean opacities are shown to be three orders of magnitude larger than results of the average-atom model.« less
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