We put together a first-principles equation of state (FPEOS) database for matter at extreme conditions by combining results from path integral Monte Carlo and density functional molecular dynamics simulations the elements H, He, B, C, N, O, Ne, Na, Mg, Al, Si as well compounds $\mathrm{LiF}, {\mathrm{B}}_{4}\mathrm{C}, \mathrm{BN}, {\mathrm{CH}}_{4}, {\mathrm{CH}}_{2}, {\mathrm{C}}_{2}{\mathrm{H}}_{3}, \mathrm{CH}, {\mathrm{C}}_{2}\mathrm{H}, \mathrm{MgO}, \mathrm{and} {\mathrm{MgSiO}}_{3}$....

We performed ab initio molecular dynamics simulations for pressures and temperatures from 300--5000 GPa 3000--30 000 K in order to determine the equation of state solid liquid iron. By employing a thermodynamic integration technique, we derive entropy Gibbs free energy both phases, which allows us construct adiabats discuss implications shock experiments. melting line by equating energies represent it Simon fit...

By combining density functional molecular dynamics simulations with a thermodynamic integration technique, we determine the free energy of metallic hydrogen and silica, SiO2, at megabar pressures thousands degrees Kelvin. Our ab initio solubility calculations show that silica dissolves into fluid above 5000 K for from 10 40 Mbars, which has implications evolution rocky cores in giant gas planets like Jupiter, Saturn, substantial fraction known extrasolar planets. findings underline necessity...

Ultrahigh-pressure phase boundary between solid and liquid SiO2 is still quite unclear. Here we present predictions of silica melting curve for the multimegabar pressure regime, as obtained from first principles molecular dynamics simulations. We calculate temperatures three high phases (pyrite-, cotunnite-, Fe2P-type SiO2) at different pressures using Z method. The computed found to rise abruptly around 330 GPa, an increase not previously reported by any This in close agreement with recent...

In order to provide a comprehensive theoretical description of ${\mathrm{MgSiO}}_{3}$ at extreme conditions, we combine results from path integral Monte Carlo and density functional molecular dynamics simulations generate consistent equation state for this material. We consider wide range temperature conditions ${10}^{4}$ ${10}^{8}\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ 0.321 64.2 $\mathrm{g}\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ (0.1- 20-fold the ambient density)....

Abstract Super-Earths and sub-Neptunes are the most common planet types in our galaxy. A subset of these planets is predicted to be water worlds, bodies that rich poor hydrogen gas. The interior structures worlds have been assumed consist surrounding a rocky mantle iron core. In small planets, rock form distinct layers with limited incorporation into silicate phases, but materials may interact differently during growth evolution due greater pressures temperatures. Here, we use density...

We use first-principles molecular dynamics simulations coupled with the thermodynamic integration method to study hexagonal close-packed (hcp) body-centered cubic (bcc) transition and melting of beryllium up a pressure 1600 GPa. derive line by equating solid liquid Gibbs free energies represent it Simon-Glatzel fit ${T}_{m}=1564\phantom{\rule{0.16em}{0ex}}\text{K}{[1+P/(15.6032\phantom{\rule{0.16em}{0ex}}\text{GPa})]}^{0.383}$, which is in good agreement previous two-phase 6000 K. also...

The motion of a block sliding on curve is well studied problem for flat and circular surfaces, but the necessary conditions to leave surface deserve deeper treatment. In this article, we generalize an arbitrary surface, including effects friction, provide general expression determine under what particle will surface. An explicit integral form speed given, which analytically integrable some cases. We demonstrate criteria critical at immediately leaves Three curves, circle, cycloid, catenary,...

The elements hydrogen, carbon, nitrogen and oxygen are assumed to comprise the bulk of interiors ice giant planets Uranus, Neptune, sub-Neptune exoplanets. details their interior structures have remained largely unknown because it is not understood how compounds H2O, NH3 CH4 behave react once they been accreted exposed high pressures temperatures. Here we study thirteen H-C-N-O with ab initio computer simulations demonstrate that assume a superionic state at elevated temperatures, in which...

The Z method is a novel technique that allows to calculate the melting temperature of materials at different pressures from microcanonical ensemble. In this work, we apply study behavior silica high pressures, determining temperatures and dynamical properties.

Using two first-principles computer simulation techniques, path integral Monte Carlo and density functional theory molecular dynamics, we derive the equation of state magnesium in regime warm dense matter, with densities ranging from 0.43 to 86.11 g cm−3 temperatures 20 000 K 5×108 K. These conditions are relevant for interiors giant planets stars as well shock compression measurements inertial confinement fusion experiments. We study ionization mechanisms electronic structure a function...

We performab initiosimulations of beryllium (Be) and magnesium oxide (MgO) at megabar pressures compare their structural thermodynamic properties. make a detailed comparison our two recently derived phase diagrams Be (Wuet al2021Phys. Rev.B104014103) MgO (Soubiran Militzer 2020Phys. Rev. Lett.125175701) using the integration technique, as they exhibit striking similarities regarding shape. explore whether Lindemann criterion can explain melting temperatures these materials through...

Ramp compression experiments characterize high-pressure states of matter at temperatures well below those present in shock compression. However, because temperature is typically not directly measured during ramp compression, it uncertain how much heating occurs under these shock-free conditions. Here, we performed a series ab initio simulations on carbon order to match the density-stress measurements Smith et al. [Smith al., Nature (London) 511, 330 (2014)]. We considered isotropically as...

We combine two first-principles computer simulation techniques, path integral Monte Carlo and density functional theory molecular dynamics, to determine the equation of state magnesium oxide in regime warm dense matter, with densities ranging from 0.35 71 g cm-3 temperatures 10 000 K 5 × 108 K. These conditions are relevant for interiors giant planets stars as well shock wave compression measurements inertial confinement fusion experiments. study electronic structure MgO ionization...

We study nonideal mixing effects in the regime of warm dense matter (WDM) by computing shock Hugoniot curves BN, MgO, and MgSiO3. First, we derive these from equations state (EOS) fully interacting systems, which were obtained using a combination path integral Monte Carlo calculations at high temperature density functional molecular dynamics simulations lower temperatures. then use ideal approximation constant pressure to rederive EOS tables individual elements. find that linear works...

Abstract Investigating water worlds presents a unique opportunity to understand the fundamental processes of planetary formation and evolution. One key aspect is characterizing interactions between rock under pressures temperatures present within these worlds. conditions for homogeneous mixing materials imperative bulk properties evolution water‐rich exoplanets. Here we use density functional molecular dynamics simulations study MgO‐H 2 O mixtures at high pressure–temperature where H occurs...

Using path integral Monte Carlo and density functional molecular dynamics (DFT-MD) simulations, we study the properties of MgSiO$_3$ enstatite in regime warm dense matter. We generate a consistent equation state (EOS) that spans across wide range temperatures densities (10$^4$--10$^7$ K 6.42--64.16 g cm$^{-3}$). derive shock Hugoniot curve, is good agreement with experiments. identify boundary between regimes thermal ionization pressure by locating where internal energy at constant...

A simple model for the stochastic evolution of defects in a material under irradiation is presented. Using master-equation formalism, we derive an expression average number terms power flux and exposure time. The reproduces qualitative behavior self-healing due to defect recombination, reaching steady-state concentration that depends on incident radiation temperature, while also suggesting particular time scale which energy most efficient producing defects, good agreement with experimental...

We explore the structural properties of Mg, MgO, and MgSiO3 liquids from ab initio computer simulations at conditions that are relevant for interiors giant planets, stars, shock compression measurements, inertial confinement fusion experiments. Using path-integral Monte Carlo density functional theory molecular dynamics, we derive equation state magnesium-rich in regime condensed warm dense matter, with densities ranging 0.32 to 86.11 g cm−3 temperatures 20,000 K 5 × 108 K. study electronic...

Determining the stable phase of binary rock-ice mixture at extreme conditions is crucial for structure and evolution models. Yet, research into interactions pressure temperature exceeding those found on Earth remains limited. The discovery new exoplanets points to some them having substantial water abundance, implying that interaction between an overlying layer ice underlying rock would occur under several megabar pressure. We determine solvus temperatures magnesium silicates across...