While exploring potential superconductors in the C-S-H ternary system using first-principles crystal structure prediction methods, we uncovered a class of hydride perovskites based on intercalation methane into an ${\mathrm{H}}_{3}\mathrm{S}$ framework. These intriguing ${\mathrm{H}}_{3}\mathrm{S}\text{\ensuremath{-}}{\mathrm{CH}}_{4}$ structures emerge as metastable at $\ensuremath{\sim}100$ GPa. Electron-phonon coupling calculations indicate that phases with ${\mathrm{CSH}}_{7}$...

Evolutionary algorithms (EAs) coupled with density functional theory (DFT) calculations have been used to predict the most stable hydrides of phosphorus (PHn, n = 1-6) at 100, 150, and 200 GPa. At these pressures phosphine is unstable respect decomposition into elemental phases, as well PH2 H2. Three metallic phases were found be dynamically superconducting between 100 One contains five formula units in primitive cell has C2/m symmetry (5FU-C2/m). It comprises 1D periodic PH3-PH-PH2-PH-PH3...

The theoretical exploration of the phase diagrams binary hydrides under pressure using ab initio crystal structure prediction techniques coupled with first principles calculations has led to in silico discovery numerous novel superconducting materials. This Perspective focuses on alkaline earth and rare polyhydrides whose critical temperature, Tc, was predicted be above boiling point liquid nitrogen. After providing a brief overview computational protocol used predict structures stable...

We report synchrotron X-ray diffraction, photoconductivity, and photoluminescence investigations of methylammonium-lead-bromide (MAPbBr3) under various stress conditions, supported by density-functional-theory (DFT) calculations. The properties MAPbBr3 show substantial dependence on the hydrostatic conditions. While nonhydrostatic compression leads to amorphization above 2.4 GPa, quasi-hydrostatic (Ar) (He) pressure, sample remains in crystalline phases. A sequence phase transitions between...

Evolutionary searches have predicted a number of ternary Ca−S−H phases that could be synthesized at pressures 100–300 GPa. P63/mmc CaSH2, Pnma Cmc21 CaSH6, and I4̅ CaSH20 were composed Ca–S lattice along with H2 molecules coordinated in "side-on" fashion to Ca. The H–H bond lengths these semiconducting elongated because σ → Ca d donation, σ* back-donation, via Kubas-like mechanism. P6̅m2 CaSH3, consisting two-dimensional HS CaH2 sheets, was metastable metallic above 128 presence van Hove...

Abstract At 80 GPa, phases with the PH 2 stoichiometry, which are composed of simple cubic like phosphorus layers capped hydrogen atoms and H molecules, predicted to be important species contributing recently observed superconductivity in compressed phosphine. The electron–phonon coupling these results from motions bound them. role mobile is decrease Coulomb repulsion between negatively charged capping layers. An insulating 5 phase, structure bonding reminiscent diborane, also metastable at...

Abstract Recently, room temperature superconductivity was measured in a carbonaceous sulfur hydride material whose identity remains unknown. Herein, first-principles calculations are performed to provide chemical basis for structural candidates derived by doping H 3 S with low levels of carbon. Pressure stabilizes unusual bonding configurations about the carbon atoms, which can be six-fold coordinated as CH 6 entities within cubic framework, or four-fold methane intercalated into H-S...

Evolutionary algorithms and the particle swarm optimization method have been used to predict stable metastable high hydrides of iron between 150-300 GPa that not discussed in previous studies. Cmca FeH5, Pmma FeH6 P2/c contain hydrogenic lattices result from slight distortions previously predicted I4/mmm FeH5 Cmmm structures. Density functional theory calculations show neither nor symmetry phases are superconducting. A P1 FeH7 phase, which is found be dynamically at 200 300 GPa, adds another...

Evolutionary structure searches revealed a plethora of stable and low-enthalpy metastable phases in the S–P–H ternary phase diagram under pressure. A wide variety crystalline types were uncovered ranging from those possessing one-dimensional chains, two-dimensional sheets based on S–H or square lattices as well P–H honeycombs, cage-like structures. Some structures could be derived doping high-pressure high-temperature superconducting Im3̅m H3S with phosphorus. Most discovered compounds...

The stability, electronic structure, and potential superconductivity in AB3Si3 (A = Na, K, Rb, Cs) compounds that assume a clathrate-based sodalite structure whose framework consists of covalent B–Si bonds are investigated via first-principles calculations. This type has recently been predicted number high-temperature superconducting hydrides, but these only stable under megabar pressures. Herein, we predict novel phase, RbB3Si3, could be synthesized pressures smaller by factor 10, ∼10 GPa,...

Abstract At 80 GPa, phases with the PH 2 stoichiometry, which are composed of simple cubic like phosphorus layers capped hydrogen atoms and H molecules, predicted to be important species contributing recently observed superconductivity in compressed phosphine. The electron–phonon coupling these results from motions bound them. role mobile is decrease Coulomb repulsion between negatively charged capping layers. An insulating 5 phase, structure bonding reminiscent diborane, also metastable at...

Tetrahydrides crystallizing in the ThCr2 Si2 structure type have been predicted to become stable for a plethora of metals under pressure, and some recently synthesized. Through detailed first-principles investigations we show that metal atoms within these I4/mmm symmetry MH4 compounds may be divalent, trivalent or tetravalent. The valence atom its radius govern bonding electronic phases, their evolution pressure. factors important enhancing superconductivity include large number hydrogenic...

Interest in Na-S compounds stems from their use battery materials at 1 atm, as well the potential for superconductivity under pressure. Evolutionary structure searches coupled with Density Functional Theory calculations were employed to predict stable and low-lying metastable phases of sodium poor rich sulfides atm within 100–200 GPa. At ambient pressures, four new or unbranched sulfur motifs predicted: Na2S3 C 2 / c Imm2 symmetry, -Na2S5 -Na2S8. Van der Waals interactions shown affect...

Evolutionary algorithms (EA) coupled with Density Functional Theory (DFT) calculations have been used to predict the most stable hydrides of phosphorous (PHn, n = 1-6) at 100, 150 and 200 GPa. At these pressures phosphine is unstable respect decomposition into elemental phases, as well PH2 H2. Three metallic phases were found be dynamically superconducting between 100-200 One contains five formula units in primitive cell has C2/m symmetry (5FU-C2/m). It comprised 1D periodic...

On compression of α-cristobalite SiO2 to pressures above approximately 12 GPa, a new polymorph known as cristobalite X-I forms. The existence has been for several decades; however, consensus regarding its exact atomic arrangement not yet reached. phase constitutes an important step in the silica densification process, separating low-density tetrahedral framework phases from high-density octahedral polymorphs. It is only nonquenchable phase, which reverts form on decompression at ambient...

Making use of first-principles calculations we analyze the effect quantum ionic fluctuations and lattice anharmonicity on crystal structure superconductivity I-43m CH4-H3S, one lowest enthalpy structures in C-S-H system, 150-300 GPa pressure range within stochastic self-consistent harmonic approximation. We predict a correction to structure, which is formed by an H3S CH4 molecules, phonon spectra, pressure-dependent superconducting critical temperatures, have been estimated previous without...

Boron substitution represents a promising approach to stabilize carbon clathrate structures, but no thermodynamically stable schemes have been identified for frameworks other than the type-VII (sodalite) structure type. To investigate possibility additional tetrahedral carbon-based networks, more 5000 unique boron decoration were investigated computationally type-I and type-II clathrates with range of guest elements including Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba. Density functional theory...

Evolutionary crystal structure prediction searches have been employed to explore the ternary Li-F-H system at 300 GPa. Metastable phases were uncovered within static lattice approximation, with LiF3H2, LiF2H, Li3F4H, LiF4H4, Li2F3H, and LiF3H lying 50 meV/atom of 0 K convex hull. All these contain HnFn+1- (n = 1, 2) anions Li+ cations. Other structural motifs such as LiF slabs, H3+ molecules, Fδ- ions are present in some low enthalpy structures. The bonding which may be bent or linear,...