---
_id: '13118'
abstract:
- lang: eng
text: Under high pressures and temperatures, molecular systems with substantial
polarization charges, such as ammonia and water, are predicted to form superionic
phases and dense fluid states with dissociating molecules and high electrical
conductivity. This behaviour potentially plays a role in explaining the origin
of the multipolar magnetic fields of Uranus and Neptune, whose mantles are thought
to result from a mixture of H2O, NH3 and CH4 ices. Determining the stability domain,
melting curve and electrical conductivity of these superionic phases is therefore
crucial for modelling planetary interiors and dynamos. Here we report the melting
curve of superionic ammonia up to 300 GPa from laser-driven shock compression
of pre-compressed samples and atomistic calculations. We show that ammonia melts
at lower temperatures than water above 100 GPa and that fluid ammonia’s electrical
conductivity exceeds that of water at conditions predicted by hot, super-adiabatic
models for Uranus and Neptune, and enhances the conductivity in their fluid water-rich
dynamo layers.
acknowledgement: We acknowledge the crucial contribution of the LULI2000 laser and
support teams to the success of the experiments. We also thank S. Brygoo and P.
Loubeyre for useful discussions. This research was supported by the French National
Research Agency (ANR) through the projects POMPEI (grant no. ANR-16-CE31-0008) and
SUPER-ICES (grant ANR-15-CE30-008-01), and by the PLAS@PAR Federation. M.F. and
R.R. gratefully acknowledge support by the DFG within the Research Unit FOR 2440.
M.B. was supported by the European Union within the Marie Skłodowska-Curie actions
(xICE grant 894725) and the NOMIS foundation. The DFT-MD calculations were performed
at the North-German Supercomputing Alliance facilities.
article_processing_charge: No
article_type: original
author:
- first_name: J.-A.
full_name: Hernandez, J.-A.
last_name: Hernandez
- first_name: Mandy
full_name: Bethkenhagen, Mandy
id: 201939f4-803f-11ed-ab7e-d8da4bd1517f
last_name: Bethkenhagen
orcid: 0000-0002-1838-2129
- first_name: S.
full_name: Ninet, S.
last_name: Ninet
- first_name: M.
full_name: French, M.
last_name: French
- first_name: A.
full_name: Benuzzi-Mounaix, A.
last_name: Benuzzi-Mounaix
- first_name: F.
full_name: Datchi, F.
last_name: Datchi
- first_name: M.
full_name: Guarguaglini, M.
last_name: Guarguaglini
- first_name: F.
full_name: Lefevre, F.
last_name: Lefevre
- first_name: F.
full_name: Occelli, F.
last_name: Occelli
- first_name: R.
full_name: Redmer, R.
last_name: Redmer
- first_name: T.
full_name: Vinci, T.
last_name: Vinci
- first_name: A.
full_name: Ravasio, A.
last_name: Ravasio
citation:
ama: Hernandez J-A, Bethkenhagen M, Ninet S, et al. Melting curve of superionic
ammonia at planetary interior conditions. Nature Physics. 2023;19:1280-1285.
doi:10.1038/s41567-023-02074-8
apa: Hernandez, J.-A., Bethkenhagen, M., Ninet, S., French, M., Benuzzi-Mounaix,
A., Datchi, F., … Ravasio, A. (2023). Melting curve of superionic ammonia at planetary
interior conditions. Nature Physics. Springer Nature. https://doi.org/10.1038/s41567-023-02074-8
chicago: Hernandez, J.-A., Mandy Bethkenhagen, S. Ninet, M. French, A. Benuzzi-Mounaix,
F. Datchi, M. Guarguaglini, et al. “Melting Curve of Superionic Ammonia at Planetary
Interior Conditions.” Nature Physics. Springer Nature, 2023. https://doi.org/10.1038/s41567-023-02074-8.
ieee: J.-A. Hernandez et al., “Melting curve of superionic ammonia at planetary
interior conditions,” Nature Physics, vol. 19. Springer Nature, pp. 1280–1285,
2023.
ista: Hernandez J-A, Bethkenhagen M, Ninet S, French M, Benuzzi-Mounaix A, Datchi
F, Guarguaglini M, Lefevre F, Occelli F, Redmer R, Vinci T, Ravasio A. 2023. Melting
curve of superionic ammonia at planetary interior conditions. Nature Physics.
19, 1280–1285.
mla: Hernandez, J. A., et al. “Melting Curve of Superionic Ammonia at Planetary
Interior Conditions.” Nature Physics, vol. 19, Springer Nature, 2023, pp.
1280–85, doi:10.1038/s41567-023-02074-8.
short: J.-A. Hernandez, M. Bethkenhagen, S. Ninet, M. French, A. Benuzzi-Mounaix,
F. Datchi, M. Guarguaglini, F. Lefevre, F. Occelli, R. Redmer, T. Vinci, A. Ravasio,
Nature Physics 19 (2023) 1280–1285.
date_created: 2023-06-04T22:01:02Z
date_published: 2023-09-01T00:00:00Z
date_updated: 2023-11-14T12:58:31Z
day: '01'
department:
- _id: BiCh
doi: 10.1038/s41567-023-02074-8
external_id:
isi:
- '000996921200001'
intvolume: ' 19'
isi: 1
language:
- iso: eng
month: '09'
oa_version: None
page: 1280-1285
publication: Nature Physics
publication_identifier:
eissn:
- 1745-2481
issn:
- 1745-2473
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
related_material:
link:
- relation: erratum
url: 10.1038/s41567-023-02130-3
scopus_import: '1'
status: public
title: Melting curve of superionic ammonia at planetary interior conditions
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 19
year: '2023'
...
---
_id: '13231'
abstract:
- lang: eng
text: We study ab initio approaches for calculating x-ray Thomson scattering spectra
from density functional theory molecular dynamics simulations based on a modified
Chihara formula that expresses the inelastic contribution in terms of the dielectric
function. We study the electronic dynamic structure factor computed from the Mermin
dielectric function using an ab initio electron-ion collision frequency in comparison
to computations using a linear-response time-dependent density functional theory
(LR-TDDFT) framework for hydrogen and beryllium and investigate the dispersion
of free-free and bound-free contributions to the scattering signal. A separate
treatment of these contributions, where only the free-free part follows the Mermin
dispersion, shows good agreement with LR-TDDFT results for ambient-density beryllium,
but breaks down for highly compressed matter where the bound states become pressure
ionized. LR-TDDFT is used to reanalyze x-ray Thomson scattering experiments on
beryllium demonstrating strong deviations from the plasma conditions inferred
with traditional analytic models at small scattering angles.
acknowledgement: "We want to thank P. Sperling, B. Witte, M. French, G. Röpke, H.
J. Lee and A. Cangi for many helpful discussions. M. S. and R. R. acknowledge support
by the Deutsche Forschungsgemeinschaft (DFG) within the Research Unit FOR 2440.
All simulations and analyses were performed at the North-German Supercomputing Alliance
(HLRN) and the ITMZ of the University of Rostock. M. B. gratefully acknowledges
support by the European Horizon 2020 programme within the Marie Sklodowska-Curie
actions (xICE grant 894725) and the\r\nNOMIS foundation. The work of T. D. was performed
under the auspices of the U.S. Department of Energy by Lawrence Livermore National
Laboratory under Contract No. DE-AC52-07NA27344."
article_number: '065207'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Maximilian
full_name: Schörner, Maximilian
last_name: Schörner
- first_name: Mandy
full_name: Bethkenhagen, Mandy
id: 201939f4-803f-11ed-ab7e-d8da4bd1517f
last_name: Bethkenhagen
orcid: 0000-0002-1838-2129
- first_name: Tilo
full_name: Döppner, Tilo
last_name: Döppner
- first_name: Dominik
full_name: Kraus, Dominik
last_name: Kraus
- first_name: Luke B.
full_name: Fletcher, Luke B.
last_name: Fletcher
- first_name: Siegfried H.
full_name: Glenzer, Siegfried H.
last_name: Glenzer
- first_name: Ronald
full_name: Redmer, Ronald
last_name: Redmer
citation:
ama: Schörner M, Bethkenhagen M, Döppner T, et al. X-ray Thomson scattering spectra
from density functional theory molecular dynamics simulations based on a modified
Chihara formula. Physical Review E. 2023;107(6). doi:10.1103/PhysRevE.107.065207
apa: Schörner, M., Bethkenhagen, M., Döppner, T., Kraus, D., Fletcher, L. B., Glenzer,
S. H., & Redmer, R. (2023). X-ray Thomson scattering spectra from density
functional theory molecular dynamics simulations based on a modified Chihara formula.
Physical Review E. American Physical Society. https://doi.org/10.1103/PhysRevE.107.065207
chicago: Schörner, Maximilian, Mandy Bethkenhagen, Tilo Döppner, Dominik Kraus,
Luke B. Fletcher, Siegfried H. Glenzer, and Ronald Redmer. “X-Ray Thomson Scattering
Spectra from Density Functional Theory Molecular Dynamics Simulations Based on
a Modified Chihara Formula.” Physical Review E. American Physical Society,
2023. https://doi.org/10.1103/PhysRevE.107.065207.
ieee: M. Schörner et al., “X-ray Thomson scattering spectra from density
functional theory molecular dynamics simulations based on a modified Chihara formula,”
Physical Review E, vol. 107, no. 6. American Physical Society, 2023.
ista: Schörner M, Bethkenhagen M, Döppner T, Kraus D, Fletcher LB, Glenzer SH, Redmer
R. 2023. X-ray Thomson scattering spectra from density functional theory molecular
dynamics simulations based on a modified Chihara formula. Physical Review E. 107(6),
065207.
mla: Schörner, Maximilian, et al. “X-Ray Thomson Scattering Spectra from Density
Functional Theory Molecular Dynamics Simulations Based on a Modified Chihara Formula.”
Physical Review E, vol. 107, no. 6, 065207, American Physical Society,
2023, doi:10.1103/PhysRevE.107.065207.
short: M. Schörner, M. Bethkenhagen, T. Döppner, D. Kraus, L.B. Fletcher, S.H. Glenzer,
R. Redmer, Physical Review E 107 (2023).
date_created: 2023-07-16T22:01:10Z
date_published: 2023-06-14T00:00:00Z
date_updated: 2023-08-02T06:30:46Z
day: '14'
department:
- _id: BiCh
doi: 10.1103/PhysRevE.107.065207
external_id:
arxiv:
- '2301.01545'
isi:
- '001020265000002'
intvolume: ' 107'
isi: 1
issue: '6'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2301.01545
month: '06'
oa: 1
oa_version: Preprint
publication: Physical Review E
publication_identifier:
eissn:
- 2470-0053
issn:
- 2470-0045
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: X-ray Thomson scattering spectra from density functional theory molecular dynamics
simulations based on a modified Chihara formula
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 107
year: '2023'
...
---
_id: '12702'
abstract:
- lang: eng
text: Hydrocarbon mixtures are extremely abundant in the Universe, and diamond formation
from them can play a crucial role in shaping the interior structure and evolution
of planets. With first-principles accuracy, we first estimate the melting line
of diamond, and then reveal the nature of chemical bonding in hydrocarbons at
extreme conditions. We finally establish the pressure-temperature phase boundary
where it is thermodynamically possible for diamond to form from hydrocarbon mixtures
with different atomic fractions of carbon. Notably, here we show a depletion zone
at pressures above 200 GPa and temperatures below 3000 K-3500 K where diamond
formation is thermodynamically favorable regardless of the carbon atomic fraction,
due to a phase separation mechanism. The cooler condition of the interior of Neptune
compared to Uranus means that the former is much more likely to contain the depletion
zone. Our findings can help explain the dichotomy of the two ice giants manifested
by the low luminosity of Uranus, and lead to a better understanding of (exo-)planetary
formation and evolution.
acknowledgement: BC thanks Daan Frenkel for stimulating discussions. We thank Aleks
Reinhardt, Daan Frenkel, Marius Millot, Federica Coppari, Rhys Bunting, and Chris
J. Pickard for critically reading the manuscript and providing useful suggestions.
BC acknowledges resources provided by the Cambridge Tier-2 system operated by the
University of Cambridge Research Computing Service funded by EPSRC Tier-2 capital
grant EP/P020259/1. SH acknowledges support from LDRD 19-ERD-031 and computing support
from the Lawrence Livermore National Laboratory (LLNL) Institutional Computing Grand
Challenge program. Lawrence Livermore National Laboratory is operated by Lawrence
Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear
Security Administration under Contract DE-AC52-07NA27344. MB acknowledges support
by the European Horizon 2020 program within the Marie Skłodowska-Curie actions (xICE
grant number 894725), funding from the NOMIS foundation and computational resources
at the North-German Supercomputing Alliance (HLRN) facilities.
article_number: '1104'
article_processing_charge: No
article_type: original
author:
- first_name: Bingqing
full_name: Cheng, Bingqing
id: cbe3cda4-d82c-11eb-8dc7-8ff94289fcc9
last_name: Cheng
orcid: 0000-0002-3584-9632
- first_name: Sebastien
full_name: Hamel, Sebastien
last_name: Hamel
- first_name: Mandy
full_name: Bethkenhagen, Mandy
id: 201939f4-803f-11ed-ab7e-d8da4bd1517f
last_name: Bethkenhagen
orcid: 0000-0002-1838-2129
citation:
ama: Cheng B, Hamel S, Bethkenhagen M. Thermodynamics of diamond formation from
hydrocarbon mixtures in planets. Nature Communications. 2023;14. doi:10.1038/s41467-023-36841-1
apa: Cheng, B., Hamel, S., & Bethkenhagen, M. (2023). Thermodynamics of diamond
formation from hydrocarbon mixtures in planets. Nature Communications.
Springer Nature. https://doi.org/10.1038/s41467-023-36841-1
chicago: Cheng, Bingqing, Sebastien Hamel, and Mandy Bethkenhagen. “Thermodynamics
of Diamond Formation from Hydrocarbon Mixtures in Planets.” Nature Communications.
Springer Nature, 2023. https://doi.org/10.1038/s41467-023-36841-1.
ieee: B. Cheng, S. Hamel, and M. Bethkenhagen, “Thermodynamics of diamond formation
from hydrocarbon mixtures in planets,” Nature Communications, vol. 14.
Springer Nature, 2023.
ista: Cheng B, Hamel S, Bethkenhagen M. 2023. Thermodynamics of diamond formation
from hydrocarbon mixtures in planets. Nature Communications. 14, 1104.
mla: Cheng, Bingqing, et al. “Thermodynamics of Diamond Formation from Hydrocarbon
Mixtures in Planets.” Nature Communications, vol. 14, 1104, Springer Nature,
2023, doi:10.1038/s41467-023-36841-1.
short: B. Cheng, S. Hamel, M. Bethkenhagen, Nature Communications 14 (2023).
date_created: 2023-03-05T23:01:04Z
date_published: 2023-02-27T00:00:00Z
date_updated: 2023-08-01T13:36:11Z
day: '27'
ddc:
- '540'
department:
- _id: BiCh
doi: 10.1038/s41467-023-36841-1
external_id:
isi:
- '000939678300002'
pmid:
- '36843123'
file:
- access_level: open_access
checksum: 5ff61ad21511950c15abb73b18613883
content_type: application/pdf
creator: cchlebak
date_created: 2023-03-07T10:58:00Z
date_updated: 2023-03-07T10:58:00Z
file_id: '12713'
file_name: 2023_NatComm_Cheng.pdf
file_size: 1946443
relation: main_file
success: 1
file_date_updated: 2023-03-07T10:58:00Z
has_accepted_license: '1'
intvolume: ' 14'
isi: 1
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
pmid: 1
project:
- _id: 9B861AAC-BA93-11EA-9121-9846C619BF3A
name: NOMIS Fellowship Program
publication: Nature Communications
publication_identifier:
eissn:
- 2041-1723
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Thermodynamics of diamond formation from hydrocarbon mixtures in planets
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 14
year: '2023'
...
---
_id: '13039'
abstract:
- lang: eng
text: We calculate reflectivities of dynamically compressed water, water-ethanol
mixtures, and ammonia at infrared and optical wavelengths with density functional
theory and molecular dynamics simulations. The influence of the exchange-correlation
functional on the results is examined in detail. Our findings indicate that the
consistent use of the HSE hybrid functional reproduces experimental results much
better than the commonly used PBE functional. The HSE functional offers not only
a more accurate description of the electronic band gap but also shifts the onset
of molecular dissociation in the molecular dynamics simulations to significantly
higher pressures. We also highlight the importance of using accurate reference
standards in reflectivity experiments and reanalyze infrared and optical reflectivity
data from recent experiments. Thus, our combined theoretical and experimental
work explains and resolves lingering discrepancies between calculations and measurements
for the investigated molecular substances under shock compression.
acknowledgement: 'We thank R. Redmer for helpful discussions. M.F. acknowledges support
by the Deutsche Forschungsgemeinschaft (DFG) within the FOR 2440. M.B. gratefully
acknowledges support by the European Horizon 2020 programme within the Marie Skłodowska-Curie
actions (xICE Grant No. 894725) and the NOMIS foundation. A.R. and J.-A.H. acknowledge
support form the French National Research Agency (ANR) through the projects POMPEI
(Grant No. ANR-16-CE31-0008) and SUPER-ICES (Grant No. ANR-15-CE30-008-01). The
ab initio calculations were performed at the NorthGerman Supercomputing Alliance
(HLRN) facilities. '
article_number: '134109'
article_processing_charge: No
article_type: original
author:
- first_name: Martin
full_name: French, Martin
last_name: French
- first_name: Mandy
full_name: Bethkenhagen, Mandy
id: 201939f4-803f-11ed-ab7e-d8da4bd1517f
last_name: Bethkenhagen
orcid: 0000-0002-1838-2129
- first_name: Alessandra
full_name: Ravasio, Alessandra
last_name: Ravasio
- first_name: Jean Alexis
full_name: Hernandez, Jean Alexis
last_name: Hernandez
citation:
ama: French M, Bethkenhagen M, Ravasio A, Hernandez JA. Ab initio calculation of
the reflectivity of molecular fluids under shock compression. Physical Review
B. 2023;107(13). doi:10.1103/PhysRevB.107.134109
apa: French, M., Bethkenhagen, M., Ravasio, A., & Hernandez, J. A. (2023). Ab
initio calculation of the reflectivity of molecular fluids under shock compression.
Physical Review B. American Physical Society. https://doi.org/10.1103/PhysRevB.107.134109
chicago: French, Martin, Mandy Bethkenhagen, Alessandra Ravasio, and Jean Alexis
Hernandez. “Ab Initio Calculation of the Reflectivity of Molecular Fluids under
Shock Compression.” Physical Review B. American Physical Society, 2023.
https://doi.org/10.1103/PhysRevB.107.134109.
ieee: M. French, M. Bethkenhagen, A. Ravasio, and J. A. Hernandez, “Ab initio calculation
of the reflectivity of molecular fluids under shock compression,” Physical
Review B, vol. 107, no. 13. American Physical Society, 2023.
ista: French M, Bethkenhagen M, Ravasio A, Hernandez JA. 2023. Ab initio calculation
of the reflectivity of molecular fluids under shock compression. Physical Review
B. 107(13), 134109.
mla: French, Martin, et al. “Ab Initio Calculation of the Reflectivity of Molecular
Fluids under Shock Compression.” Physical Review B, vol. 107, no. 13, 134109,
American Physical Society, 2023, doi:10.1103/PhysRevB.107.134109.
short: M. French, M. Bethkenhagen, A. Ravasio, J.A. Hernandez, Physical Review B
107 (2023).
date_created: 2023-05-21T22:01:04Z
date_published: 2023-04-01T00:00:00Z
date_updated: 2023-08-01T14:45:25Z
day: '01'
department:
- _id: BiCh
doi: 10.1103/PhysRevB.107.134109
external_id:
isi:
- '000974672600001'
intvolume: ' 107'
isi: 1
issue: '13'
language:
- iso: eng
month: '04'
oa_version: None
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Ab initio calculation of the reflectivity of molecular fluids under shock compression
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 107
year: '2023'
...