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Title: Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas

Abstract

Carbon-hydrogen plasmas and hydrocarbon materials are of broad interest to laser shock experimentalists, high energy density physicists, and astrophysicists. Accurate equations of state (EOSs) of hydrocarbons are valuable for various studies from inertial confinement fusion to planetary science. By combining path integral Monte Carlo (PIMC) results at high temperatures and density functional theory molecular dynamics results at lower temperatures, we compute the EOSs for hydrocarbons from simulations performed at 1473 separate (ρ, T)-points distributed over a range of compositions. These methods accurately treat electronic excitation effects with neither adjustable parameter nor experimental input. PIMC is also an accurate simulation method that is capable of treating many-body interaction and nuclear quantum effects at finite temperatures. These methods therefore provide a benchmark-quality EOS that surpasses that of semi-empirical and Thomas-Fermi-based methods in the warm dense matter regime. By comparing our first-principles EOS to the LEOS 5112 model for CH, we validate the specific heat assumptions in this model but suggest that the Grüneisen parameter is too large at low temperatures. Based on our first-principles EOSs, we predict the principal Hugoniot curve of polystyrene to be 2%-5% softer at maximum shock compression than that predicted by orbital-free density functional theory and SESAME 7593.more » By investigating the atomic structure and chemical bonding of hydrocarbons, we show a drastic decrease in the lifetime of chemical bonds in the pressure interval from 0.4 to 4 megabar. We find the assumption of linear mixing to be valid for describing the EOS and the shock Hugoniot curve of hydrocarbons in the regime of partially ionized atomic liquids. We make predictions of the shock compression of glow-discharge polymers and investigate the effects of oxygen content and C:H ratio on its Hugoniot curve. In conclusion, our full suite of first-principles simulation results may be used to benchmark future theoretical investigations pertaining to hydrocarbon EOSs and should be helpful in guiding the design of future experiments on hydrocarbons in the gigabar regime.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [2];  [3];  [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1474357
Alternate Identifier(s):
OSTI ID: 1420621
Report Number(s):
LLNL-JRNL-736960
Journal ID: ISSN 0021-9606; 889714
Grant/Contract Number:  
AC52-07NA27344; NA0001859; SC0010517; SC0016248
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 148; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Zhang, Shuai, Militzer, Burkhard, Benedict, Lorin X., Soubiran, François, Sterne, Philip A., and Driver, Kevin P.. Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas. United States: N. p., 2017. Web. doi:10.1063/1.5001208.
Zhang, Shuai, Militzer, Burkhard, Benedict, Lorin X., Soubiran, François, Sterne, Philip A., & Driver, Kevin P.. Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas. United States. doi:10.1063/1.5001208.
Zhang, Shuai, Militzer, Burkhard, Benedict, Lorin X., Soubiran, François, Sterne, Philip A., and Driver, Kevin P.. Mon . "Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas". United States. doi:10.1063/1.5001208.
@article{osti_1474357,
title = {Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas},
author = {Zhang, Shuai and Militzer, Burkhard and Benedict, Lorin X. and Soubiran, François and Sterne, Philip A. and Driver, Kevin P.},
abstractNote = {Carbon-hydrogen plasmas and hydrocarbon materials are of broad interest to laser shock experimentalists, high energy density physicists, and astrophysicists. Accurate equations of state (EOSs) of hydrocarbons are valuable for various studies from inertial confinement fusion to planetary science. By combining path integral Monte Carlo (PIMC) results at high temperatures and density functional theory molecular dynamics results at lower temperatures, we compute the EOSs for hydrocarbons from simulations performed at 1473 separate (ρ, T)-points distributed over a range of compositions. These methods accurately treat electronic excitation effects with neither adjustable parameter nor experimental input. PIMC is also an accurate simulation method that is capable of treating many-body interaction and nuclear quantum effects at finite temperatures. These methods therefore provide a benchmark-quality EOS that surpasses that of semi-empirical and Thomas-Fermi-based methods in the warm dense matter regime. By comparing our first-principles EOS to the LEOS 5112 model for CH, we validate the specific heat assumptions in this model but suggest that the Grüneisen parameter is too large at low temperatures. Based on our first-principles EOSs, we predict the principal Hugoniot curve of polystyrene to be 2%-5% softer at maximum shock compression than that predicted by orbital-free density functional theory and SESAME 7593. By investigating the atomic structure and chemical bonding of hydrocarbons, we show a drastic decrease in the lifetime of chemical bonds in the pressure interval from 0.4 to 4 megabar. We find the assumption of linear mixing to be valid for describing the EOS and the shock Hugoniot curve of hydrocarbons in the regime of partially ionized atomic liquids. We make predictions of the shock compression of glow-discharge polymers and investigate the effects of oxygen content and C:H ratio on its Hugoniot curve. In conclusion, our full suite of first-principles simulation results may be used to benchmark future theoretical investigations pertaining to hydrocarbon EOSs and should be helpful in guiding the design of future experiments on hydrocarbons in the gigabar regime.},
doi = {10.1063/1.5001208},
journal = {Journal of Chemical Physics},
number = 10,
volume = 148,
place = {United States},
year = {Mon Nov 20 00:00:00 EST 2017},
month = {Mon Nov 20 00:00:00 EST 2017}
}

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Works referenced in this record:

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