Liquid Iron Equation of State to the Terapascal Regime From Ab Initio Simulations

2019 ◽  
Vol 124 (4) ◽  
pp. 3350-3364 ◽  
Author(s):  
Fabian Wagle ◽  
Gerd Steinle‐Neumann
Keyword(s):  
Equation Of State ◽  
Ab Initio ◽  
Liquid Iron ◽  
Ab Initio Simulations

Equation of state and phase diagram of ammonia at high pressures from ab initio simulations

2013 ◽  
Vol 138 (23) ◽  
pp. 234504 ◽  
Author(s):  
Mandy Bethkenhagen ◽  
Martin French ◽  
Ronald Redmer
Keyword(s):  
Phase Diagram ◽  
Equation Of State ◽  
Ab Initio ◽  
High Pressures ◽  
Ab Initio Simulations

Exploring the deep interior of ice giants with shock-compression experiments and ab initio simulations: The case of metallic ammonia 

2021 ◽  
Author(s):  
Mandy Bethkenhagen ◽  
Jean-Alexis Hernandez ◽  
Alessandra Benuzzi-Mounaix ◽  
Frederic Datchi ◽  
Martin French ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Equation Of State ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Physical Review ◽  
Gradual Transition ◽  
Chemical Physics ◽  
Ab Initio Simulations ◽  
Plasma State

<p>Ammonia is predicted to be one of the major components in the depths of the ice giant planets Uranus and Neptune. Their dynamics, evolution, and interior structure are insufficiently understood and models rely imperatively on data for equation of state and transport properties [1,2]. Despite its great significance, the experimentally accessed region of the ammonia phase diagram today is still very limited in pressure and temperature [3, 4].</p><p>We investigate the equation of state, the optical properties and the electrical conductivity of warm dense ammonia by combining laser-driven shock experiments and state-of-the-art density functional theory molecular dynamics (DFT-MD) simulations [5]. The equation of state is probed along the Hugoniot of liquid NH<sub>3 </sub>up to 350 GPa and 40000 K and in very good agreement with earlier DFT-MD results [6]. Our temperature measurements show a subtle slope change at 7000 K and 90 GPa, which coincides with the gradual transition from a liquid dominated by molecules to a plasma state in our new ab initio simulations. The reflectivity data furnish the first experimental evidence of electronic conduction in high pressure ammonia and are in excellent agreement with the reflectivity computed from atomistic simulations. Corresponding electrical conductivity values are found up to one order of magnitude higher than in water in the 100 GPa regime, with possible implications on the generation of magnetic dynamos in large icy planets’ interiors.</p><p> </p><p>[1] Scheibe, Nettelmann, Redmer, Astronomy & Astrophysics <strong>632</strong>, A70 (2019).</p><p>[2] Vazan & Helled, Astronomy & Astrophysics <strong>633</strong>, A50 (2020).</p><p>[3] Nellis, Hamilton, Holmes, Radousky, Ree, Mitchell, Nicol, Science <strong>240</strong>, 779 (1988).</p><p>[4] Radousky, Mitchell, Nellis, Journal of Chemical Physics <strong>93</strong>, 8235 (1990).</p><p>[5] Ravasio, Bethkenhagen, Hernandez, Benuzzi-Mounaix, Datchi, French, Guarguaglini, Lefevre, Ninet, Redmer, Vinci, Physical Review Letters <strong>126</strong>, 025003 (2021).</p><p>[6] Bethkenhagen, French, Redmer, Journal of Chemical Physics <strong>138</strong>, 234504 (2013).</p>

Quantum Mechanical Interpretation of the Ultra-Low Energy Methyl-Rotation Dynamics in Porous Metal-Organic Frameworks Probed by Low-Frequency Vibrational Spectroscopy and ab initio Simulations

2018 ◽  
Author(s):  
Qi Li ◽  
Adam J. Zaczek ◽  
Timothy M. Korter ◽  
J. Axel Zeitler ◽  
Michael T. Ruggiero
Keyword(s):  
Ab Initio ◽  
Metal Organic Frameworks ◽  
Low Frequency ◽  
Rotor Dynamics ◽  
Quantum Mechanical ◽  
Valuable Insight ◽  
Void Space ◽  
Ab Initio Simulations ◽  
Metal Organic ◽  
Insight Into

<div>Understanding the nature of the interatomic interactions present within the pores of metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 and its cobalt analogue</div><div>ZIF-67, the imidazolate methyl-groups, which point directly</div><div>into the void space, have been shown to freely rotate - even</div><div>down to cryogenic temperatures. Using a combination of ex-</div><div>perimental terahertz time-domain spectroscopy, low-frequency</div><div>Raman spectroscopy, and state-of-the-art ab initio simulations,</div><div>the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully charac-</div><div>terized within the context of a quantum-mechanical hindered-</div><div>rotor model. The results lend insight into the fundamental</div><div>origins of the experimentally observed methyl-rotor dynamics,</div><div>and provide valuable insight into the nature of the weak inter-</div><div>actions present within this important class of materials.</div>

scholarly journals Early-stage formation of (hydr)oxo bridges in transition-metal catalysts for photosynthetic processes

2021 ◽  
Author(s):  
Shin Nakamura ◽  
Matteo Capone ◽  
Giuseppe Mattioli ◽  
Leonardo Guidoni
Keyword(s):  
Transition Metal ◽  
Aqueous Solutions ◽  
Ab Initio ◽  
Early Stage ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Electrochemical Potential ◽  
Ab Initio Simulations

Water-oxidizing metal-(hydr)oxo catalyst films can be generally deposited and activated by applying a positive electrochemical potential to suitable starting aqueous solutions. Here, we used ab initio simulations based on density...

scholarly journals The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

2017 ◽  
Vol 45 (4) ◽  
pp. 311-322 ◽  
Author(s):  
Clément Jakymiw ◽  
Lidunka Vočadlo ◽  
David P. Dobson ◽  
Edward Bailey ◽  
Andrew R. Thomson ◽  
...  
Keyword(s):  
Ab Initio ◽  
Phase Diagrams ◽  
Ab Initio Simulations
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