# First-principles equation of state and electronic properties of warm dense oxygen

## Abstract

In this paper, we perform all-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of oxygen. Our simulations cover a wide density-temperature range of 1–100 g cm ^{-3} and 10 ^{4}–10 ^{9} K. By combining results from PIMC and DFT-MD, we are able to compute pressures and internal energies from first-principles at all temperatures and provide a coherent equation of state. We compare our first-principles calculations with analytic equations of state, which tend to agree for temperatures above 8 × 10 ^{6} K. Pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. As we increase the density at constant temperature, we find that the ionization fraction of the 1s state decreases while the other electronic states move towards the continuum. The computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized.

- Authors:

- Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science
- Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science. Dept. of Astronomy

- Publication Date:

- Research Org.:
- Univ. of California, Berkeley, CA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Science Foundation (NSF)

- OSTI Identifier:
- 1469578

- Alternate Identifier(s):
- OSTI ID: 1224336

- Grant/Contract Number:
- SC0010517; CNS-0821794

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Journal of Chemical Physics

- Additional Journal Information:
- Journal Volume: 143; Journal Issue: 16; Journal ID: ISSN 0021-9606

- Publisher:
- American Institute of Physics (AIP)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; shock compression; density functional theory; Monte Carlo methods; chemical elements; equations of state; Hugoniot curve; degenerate stars; classical statistical mechanics; molecular dynamics; density of states

### Citation Formats

```
Driver, K. P., Soubiran, F., Zhang, Shuai, and Militzer, B.
```*First-principles equation of state and electronic properties of warm dense oxygen*. United States: N. p., 2015.
Web. doi:10.1063/1.4934348.

```
Driver, K. P., Soubiran, F., Zhang, Shuai, & Militzer, B.
```*First-principles equation of state and electronic properties of warm dense oxygen*. United States. doi:10.1063/1.4934348.

```
Driver, K. P., Soubiran, F., Zhang, Shuai, and Militzer, B. Tue .
"First-principles equation of state and electronic properties of warm dense oxygen". United States.
doi:10.1063/1.4934348. https://www.osti.gov/servlets/purl/1469578.
```

```
@article{osti_1469578,
```

title = {First-principles equation of state and electronic properties of warm dense oxygen},

author = {Driver, K. P. and Soubiran, F. and Zhang, Shuai and Militzer, B.},

abstractNote = {In this paper, we perform all-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of oxygen. Our simulations cover a wide density-temperature range of 1–100 g cm-3 and 104–109 K. By combining results from PIMC and DFT-MD, we are able to compute pressures and internal energies from first-principles at all temperatures and provide a coherent equation of state. We compare our first-principles calculations with analytic equations of state, which tend to agree for temperatures above 8 × 106 K. Pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. As we increase the density at constant temperature, we find that the ionization fraction of the 1s state decreases while the other electronic states move towards the continuum. The computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized.},

doi = {10.1063/1.4934348},

journal = {Journal of Chemical Physics},

number = 16,

volume = 143,

place = {United States},

year = {Tue Oct 27 00:00:00 EDT 2015},

month = {Tue Oct 27 00:00:00 EDT 2015}

}

*Citation information provided by*

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Web of Science

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