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Title: Ab initio modeling of nonequilibrium electron-ion dynamics of iron in the warm dense matter regime

Here, the spatiotemporal electron and ion relaxation dynamics of iron induced by femtosecond laser pulses was studied using a one-dimensional two-temperature model (1D-TTM) where electron and ion temperature-dependent thermophysical parameters such as specific heat ( C), electron-phonon coupling ( G), and thermal conductivity ( K) were calculated with ab initio density-functional-theory (DFT) simulations. Based on the simulated time evolutions of electron and ion temperature distributions [ Te( x,t) and T i( x,t)], the time evolution of x-ray absorption near-edge spectroscopy (XANES) was calculated and compared with experimental results reported by Fernandez-Pañella et al., where the slope of XANES spectrum at the onset of absorption (s) was used due to its excellent sensitivity to the electron temperature. Our results indicate that the ion temperature dependence on G and C, which is largely neglected in the past studies, is very important for studying the nonequilibrium electron-ion relaxation dynamics of iron in warm dense matter (WDM) conditions. It is also shown that the 1/s behavior becomes very sensitive to the thermal gradient profile, in other words, to the values of K in a TTM simulation, for target thickness of about two to four times the mean free path of conduction electrons. Our approachmore » based on 1D-TTM and XANES simulations can be used to determine the optimal combination of target geometry and laser fluence for a given target material, which will enable us to tightly constrain the thermophysical parameters under electron-ion nonequilibrium WDM conditions.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC52-07NA27344; FWP-SCW1264; AC02-05CH11231; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 21; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1457785

Ogitsu, T., Fernandez-Panella, A., Hamel, S., Correa, A. A., Prendergast, D., Pemmaraju, C. D., and Ping, Y.. Ab initio modeling of nonequilibrium electron-ion dynamics of iron in the warm dense matter regime. United States: N. p., Web. doi:10.1103/physrevb.97.214203.
Ogitsu, T., Fernandez-Panella, A., Hamel, S., Correa, A. A., Prendergast, D., Pemmaraju, C. D., & Ping, Y.. Ab initio modeling of nonequilibrium electron-ion dynamics of iron in the warm dense matter regime. United States. doi:10.1103/physrevb.97.214203.
Ogitsu, T., Fernandez-Panella, A., Hamel, S., Correa, A. A., Prendergast, D., Pemmaraju, C. D., and Ping, Y.. 2018. "Ab initio modeling of nonequilibrium electron-ion dynamics of iron in the warm dense matter regime". United States. doi:10.1103/physrevb.97.214203.
@article{osti_1457785,
title = {Ab initio modeling of nonequilibrium electron-ion dynamics of iron in the warm dense matter regime},
author = {Ogitsu, T. and Fernandez-Panella, A. and Hamel, S. and Correa, A. A. and Prendergast, D. and Pemmaraju, C. D. and Ping, Y.},
abstractNote = {Here, the spatiotemporal electron and ion relaxation dynamics of iron induced by femtosecond laser pulses was studied using a one-dimensional two-temperature model (1D-TTM) where electron and ion temperature-dependent thermophysical parameters such as specific heat (C), electron-phonon coupling (G), and thermal conductivity (K) were calculated with ab initio density-functional-theory (DFT) simulations. Based on the simulated time evolutions of electron and ion temperature distributions [Te(x,t) and Ti(x,t)], the time evolution of x-ray absorption near-edge spectroscopy (XANES) was calculated and compared with experimental results reported by Fernandez-Pañella et al., where the slope of XANES spectrum at the onset of absorption (s) was used due to its excellent sensitivity to the electron temperature. Our results indicate that the ion temperature dependence on G and C, which is largely neglected in the past studies, is very important for studying the nonequilibrium electron-ion relaxation dynamics of iron in warm dense matter (WDM) conditions. It is also shown that the 1/s behavior becomes very sensitive to the thermal gradient profile, in other words, to the values of K in a TTM simulation, for target thickness of about two to four times the mean free path of conduction electrons. Our approach based on 1D-TTM and XANES simulations can be used to determine the optimal combination of target geometry and laser fluence for a given target material, which will enable us to tightly constrain the thermophysical parameters under electron-ion nonequilibrium WDM conditions.},
doi = {10.1103/physrevb.97.214203},
journal = {Physical Review B},
number = 21,
volume = 97,
place = {United States},
year = {2018},
month = {6}
}

Works referenced in this record:

Generalized Gradient Approximation Made Simple
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  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865