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Title: Optical properties of highly compressed polystyrene: An ab initio study

Using all-electron density functional theory, we have performed an ab initio study on x ray absorption spectra of highly compressed polystyrene (CH). Here, we found that the K-edge shifts in strongly coupled, degenerate polystyrene cannot be explained by existing continuum-lowering models adopted in traditional plasma physics. To gain insights into the K edge shift in warm, dense CH, we have developed a model designated as “single-mixture-in-a-box” (SMIAB), which incorporates both the lowering of continuum and the rising of Fermi surface resulting from high compression. This simple SMIAB model correctly predicts the K-edge shift of carbon in highly compressed CH in good agreement with results from quantum-molecular-dynamics (QMD) calculations. Traditional opacity models failed to give the proper K-edge shifts as the CH density increased. Based on QMD calculations, we have established a first-principles opacity table (FPOT) for CH in a wide range of densities and temperatures [p = 0.1 to 100 g/cm 3 and T = 2000 to 1,000,000 K]. The FPOT gives much higher Rosseland mean opacity compared to the cold-opacity–patched astrophysics opacity table for warm, dense CH and favorably compares to the newly improved Los Alamos ATOMIC model for moderately compressed CH (pCH ≤10 g/cm 3) but remains amore » factor of 2 to 3 higher at extremely high densities (pCH ≥ 50 g/cm 3). We anticipate the established FPOT of CH will find important applications to reliable designs of high-energy-density experiments. Moreover, the understanding of K-edge shifting revealed in this study could provide guides for improving the traditional opacity models to properly handle the strongly coupled and degenerate conditions.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [2]
  1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
2017-98; 1354
Journal ID: ISSN 2469-9950; PRBMDO; 2017-98, 2309, 1354
Grant/Contract Number:
NA0001944; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 14; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Univ. of Rochester, NY (United States). Lab. for Laser Energetics
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; cs.DB; H.2.8
OSTI Identifier:
1399472
Alternate Identifier(s):
OSTI ID: 1399627