相关论文: Theoretical investigation of methane under pressur…

We have performed a combined experimental and theoretical study of ethane and methane at high pressures up to 120 GPa at 300 K using x-ray diffraction and Raman spectroscopy and the USPEX ab-initio evolutionary structural search algorithm,…

By employing first-principles metadynamics simulations, we explore the 300 K structures of solid hydrogen over the pressure range 150-300 GPa. At 200 GPa, we find the ambient-pressure disordered hexagonal close-packed (hcp) phase transited…

We have performed quantum molecular-dynamics simulations for methane under shock compressions up to 80 GPa. We obtain good agreement with available experimental data for the principal Hugoniot, derived from the equation of state. A…

Using density functional theory molecular dynamics simulations, we predict shock Hugoniot curves of precompressed methane up to 75000 K for initial densities ranging from 0.35 to 0.70 g/cc. At 4000 K, we observe the transformation into a…

We report new results on the liquid to solid phase transition of benzene. We determine experimentally and investigate the properties of a number of parameters of the benzene metastable state under different pressures (from 0.1 up to 2200…

A concentration-saturated helium mixture at the melting pressure consists of two liquid phases and one or two solid phases. The equilibrium system is univariant, whose properties depend uniquely on temperature. Four coexisting phases can…

Single-crystal synchrotron X-ray diffraction, Raman spectroscopy, and first principles calculations have been used to identify the structure of the high-pressure (HP) phase of molecular methane above 20 GPa up to 71 GPa. The structure of HP…

Experiments and computer simulations have shown that the melt-ing temperature of solid hydrogen drops with pressure above about 65 GPa, suggesting that a liquid state might exist at low temperatures. It has also been suggested that this low…

Dielectric response in methanol measured in wide pressure and temperature range ($P < 6.0$ GPa; 100 K $<T<$ 360 K) reveals a series of anomalies which can be interpreted as a transformation between several solid phases of methanol including…

Understanding the high-pressure behavior of C-H system is of great importance due to its key role in organic, bio-, petroleum and planetary chemistry. We have performed a systematic investigation of the pressure-composition phase diagram of…

Ab initio molecular dynamic method within the framework of density functional theory is applied to analyze the structural and electronic properties of crystalline molecular hydrogen at temperature 100\,K. Pressure, pair correlation function…

The structural, electronic, and spectroscopic properties of a high-pressure phase of methane hydrate (MH-III) are studied by first principles electronic structure calculations. A detailed analysis of the atomic positions suggests that {\it…

The molecular phase of hydrogen converts to the atomic metallic phase at high pressures estimated usually as 300 - 500 GPa. We analyze the decay of metallic phase as the pressure is relieved below the transition one. The metallic state is…

We have produced and observed metastable solid helium-4 below its melting pressure between 1.1 K and 1.4 K. This is achieved by an intense pressure wave carefully focused inside a crystal of known orientation. An accurate density map of the…

Methane is the simplest hydrocarbon, yet it exhibits an extraordinarily complicated series of crystal phases. Notably, the non-plastic phases have large unit cells with nearly, but not quite cubic symmetry. Furthermore, although non-polar…

Hydrogen is the most abundant element in the universe, and its properties under conditions of high temperature and pressure are crucial to understand the interior of of large gaseous planets and other astrophysical bodies. At ultra high…

We investigated numerically the high-temperature/high-pressure phase diagram of Xenon as modelled through the exp-6 interaction potential, which is thought to provide a reliable description of the thermal behaviour of rare gases under…

We survey the phase diagram of high-pressure molecular hydrogen with path integral molecular dynamics using a machine-learned interatomic potential trained with Quantum Monte Carlo forces and energies. Besides the HCP and C2/c-24 phases, we…

Molecular dynamics simulations are utilized to study the melting transition in pentane (C5H12) and heptane (C7H16), physisorbed onto the basal plane of graphite at near-monolayer coverages. Through use of the newest, optimized version of…

Results of X-ray diffraction experiments on solid oxygen at low temperature and at pressures up to 10 GPa are presented.A careful sample preparation and annealing around 240 K allowed to obtain very good diffraction patterns in the…