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Title: A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions

Here, we present a new DFTB-p3b density functional tight binding model for hydrogen at extremely high pressures and temperatures, which includes a polarizable basis set ( p) and a three-body environmentally dependent repulsive potential ( 3b). We find that use of an extended basis set is necessary under dissociated liquid conditions to account for the substantial p-orbital character of the electronic states around the Fermi energy. The repulsive energy is determined through comparison to cold curve pressures computed from density functional theory (DFT) for the hexagonal close-packed solid, as well as pressures from thermally equilibrated DFT-MD simulations of the liquid phase. In particular, we observe improved agreement in our DFTB-p3b model with previous theoretical and experimental results for the shock Hugoniot of hydrogen up to 100 GPa and 25000 K, compared to a standard DFTB model using pairwise interactions and an s-orbital basis set, only. In conclusion, the DFTB-p3b approach discussed here provides a general method to extend the DFTB method for a wide variety of materials over a significantly larger range of thermodynamic conditions than previously possible.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4]
  1. The Pennsylvania State Univ., University Park, PA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Univ. of Ontario Institute of Technology, Oshawa, ON (Canada)
  4. Univ. of Wisconsin-Madison, Madison, WI (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-652668
Journal ID: ISSN 1089-5639; 773400
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 118; Journal Issue: 29; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; semi-empirical methods; density functional tight binding; hydrogen; shock compression; extreme conditions
OSTI Identifier:
1466917

Srinivasan, Sriram Goverapet, Goldman, Nir, Tamblyn, Isaac, Hamel, Sebastien, and Gaus, Michael. A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions. United States: N. p., Web. doi:10.1021/jp5036713.
Srinivasan, Sriram Goverapet, Goldman, Nir, Tamblyn, Isaac, Hamel, Sebastien, & Gaus, Michael. A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions. United States. doi:10.1021/jp5036713.
Srinivasan, Sriram Goverapet, Goldman, Nir, Tamblyn, Isaac, Hamel, Sebastien, and Gaus, Michael. 2014. "A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions". United States. doi:10.1021/jp5036713. https://www.osti.gov/servlets/purl/1466917.
@article{osti_1466917,
title = {A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions},
author = {Srinivasan, Sriram Goverapet and Goldman, Nir and Tamblyn, Isaac and Hamel, Sebastien and Gaus, Michael},
abstractNote = {Here, we present a new DFTB-p3b density functional tight binding model for hydrogen at extremely high pressures and temperatures, which includes a polarizable basis set (p) and a three-body environmentally dependent repulsive potential (3b). We find that use of an extended basis set is necessary under dissociated liquid conditions to account for the substantial p-orbital character of the electronic states around the Fermi energy. The repulsive energy is determined through comparison to cold curve pressures computed from density functional theory (DFT) for the hexagonal close-packed solid, as well as pressures from thermally equilibrated DFT-MD simulations of the liquid phase. In particular, we observe improved agreement in our DFTB-p3b model with previous theoretical and experimental results for the shock Hugoniot of hydrogen up to 100 GPa and 25000 K, compared to a standard DFTB model using pairwise interactions and an s-orbital basis set, only. In conclusion, the DFTB-p3b approach discussed here provides a general method to extend the DFTB method for a wide variety of materials over a significantly larger range of thermodynamic conditions than previously possible.},
doi = {10.1021/jp5036713},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 29,
volume = 118,
place = {United States},
year = {2014},
month = {6}
}