## Equations of state and stability of MgSiO _{3} perovskite and post-perovskite phases from quantum Monte Carlo simulations

## Abstract

In this study, we have performed quantum Monte Carlo (QMC) simulations and density functional theory calculations to study the equations of state of MgSiO _{3} perovskite (Pv, bridgmanite) and post-perovskite (PPv) up to the pressure and temperature conditions of the base of Earth's lower mantle. The ground-state energies were derived using QMC simulations and the temperature-dependent Helmholtz free energies were calculated within the quasiharmonic approximation and density functional perturbation theory. The equations of state for both phases of MgSiO _{3} agree well with experiments, and better than those from generalized gradient approximation calculations. The Pv-PPv phase boundary calculated from our QMC equations of state is also consistent with experiments, and better than previous local density approximation calculations. Lastly, we discuss the implications for double crossing of the Pv-PPv boundary in the Earth.

- Authors:

- Carnegie Inst. of Washington, Washington, DC (United States)
- Carnegie Inst. of Washington, Washington, DC (United States) ; Univ. College London, London (United Kingdom)
- Univ. of California, Berkeley, CA (United States); University of Leeds, Leeds (United Kingdom)
- Univ. of California, Berkeley, CA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

- Publication Date:

- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

- OSTI Identifier:
- 1265284

- Alternate Identifier(s):
- OSTI ID: 1180773

- Grant/Contract Number:
- AC05-00OR22725; SC0010517; AC04-94AL85000

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physical Review B

- Additional Journal Information:
- Journal Volume: 90; Journal Issue: 18; Journal ID: ISSN 2469-9950

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 58 GEOSCIENCES

### Citation Formats

```
Lin, Yangzheng, Cohen, Ronald E., Stackhouse, Stephen, Driver, Kevin P., Militzer, Burkhard, Shulenburger, Luke, and Kim, Jeongnim. Equations of state and stability of MgSiO3 perovskite and post-perovskite phases from quantum Monte Carlo simulations. United States: N. p., 2014.
Web. doi:10.1103/PhysRevB.90.184103.
```

```
Lin, Yangzheng, Cohen, Ronald E., Stackhouse, Stephen, Driver, Kevin P., Militzer, Burkhard, Shulenburger, Luke, & Kim, Jeongnim. Equations of state and stability of MgSiO3 perovskite and post-perovskite phases from quantum Monte Carlo simulations. United States. doi:10.1103/PhysRevB.90.184103.
```

```
Lin, Yangzheng, Cohen, Ronald E., Stackhouse, Stephen, Driver, Kevin P., Militzer, Burkhard, Shulenburger, Luke, and Kim, Jeongnim. Mon .
"Equations of state and stability of MgSiO3 perovskite and post-perovskite phases from quantum Monte Carlo simulations". United States. doi:10.1103/PhysRevB.90.184103. https://www.osti.gov/servlets/purl/1265284.
```

```
@article{osti_1265284,
```

title = {Equations of state and stability of MgSiO3 perovskite and post-perovskite phases from quantum Monte Carlo simulations},

author = {Lin, Yangzheng and Cohen, Ronald E. and Stackhouse, Stephen and Driver, Kevin P. and Militzer, Burkhard and Shulenburger, Luke and Kim, Jeongnim},

abstractNote = {In this study, we have performed quantum Monte Carlo (QMC) simulations and density functional theory calculations to study the equations of state of MgSiO3 perovskite (Pv, bridgmanite) and post-perovskite (PPv) up to the pressure and temperature conditions of the base of Earth's lower mantle. The ground-state energies were derived using QMC simulations and the temperature-dependent Helmholtz free energies were calculated within the quasiharmonic approximation and density functional perturbation theory. The equations of state for both phases of MgSiO3 agree well with experiments, and better than those from generalized gradient approximation calculations. The Pv-PPv phase boundary calculated from our QMC equations of state is also consistent with experiments, and better than previous local density approximation calculations. Lastly, we discuss the implications for double crossing of the Pv-PPv boundary in the Earth.},

doi = {10.1103/PhysRevB.90.184103},

journal = {Physical Review B},

number = 18,

volume = 90,

place = {United States},

year = {2014},

month = {11}

}

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Works referenced in this record:

##
Self-Consistent Equations Including Exchange and Correlation Effects

journal, November 1965

- Kohn, W.; Sham, L. J.
- Physical Review, Vol. 140, Issue 4A, p. A1133-A1138