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Related papers: Hexagonal structure of phase III of solid hydrogen

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We present results predicting experimentally measurable structural quantities from molecular dynamics studies of hydrogen. In doing this, we propose a paradigm shift for experimentalists -- that the predictions from such calculations should…

Materials Science · Physics 2020-03-25 Graeme J. Ackland , John S. Loveday

We have studied dense hydrogen and deuterium experimentally up to 320 GPa and using ab initio molecular dynamic (MD) simulations up to 370 GPa between 250 and 300 K. Raman and optical absorption spectra show significant anharmonic and…

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…

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…

Materials Science · Physics 2020-01-07 Anastasia S. Naumova , Sergey V. Lepeshkin , Artem R. Oganov

The structure of solid oxygen has been studied at pressures from 50 to 140~GPa using static structure search methods and molecular dynamics simulations with density functional theory and a hybrid exchange functional. Several crystalline…

Materials Science · Physics 2023-09-26 Sabri F. Elatresh , V. Askarpour , S. A. Bonev

Identifying the atomic structure and properties of solid hydrogen under high pressures is a long-standing problem of high-pressure physics with far-reaching significance in planetary and materials science. Determining the…

Materials Science · Physics 2020-04-16 Ke Liao , Xin-Zheng Li , Ali Alavi , Andreas Grüneis

Gas hydrates are systems of prime importance. In particular, hydrogen hydrates are potential materials of icy satellites and comets, and may be used for hydrogen storage. We explore the H2O-H2 system at pressures in the range 0-100 GPa with…

Materials Science · Physics 2014-04-01 Guang-Rui Qian , Andriy O. Lyakhov , Qiang Zhu , Artem R. Oganov , Xiao Dong

Evolutionary structure searches predict three new phases of iodine polyhydrides stable under pressure. Insulating P1-H5I, consisting of zigzag chains of HI (delta+)and H2(delta-) molecules, is stable between 30-90 GPa. Cmcm-H2I and…

Materials Science · Physics 2015-12-15 Andrew Shamp , Eva Zurek

The interplay between electron correlation and nuclear quantum effects makes our understanding of elemental hydrogen a formidable challenge. Here, we present the phase diagram of hydrogen and deuterium at low temperatures and high-pressure…

Materials Science · Physics 2023-06-28 Lorenzo Monacelli , Michele Casula , Kosuke Nakano , Sandro Sorella , Francesco Mauri

Evolutionary algorithms and the particle swarm optimization method have been used to predict stable and metastable high hydrides of iron between 150-300 GPa that have not been discussed in previous studies. Cmca FeH5, Pmma FeH6 and P2/c…

Superconductivity · Physics 2018-10-31 Niloofar Zarifi , Tiange Bi , Hanyu Liu , Eva Zurek

Ab initio random structure searching with density functional theory was used to determine the zero-temperature structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including zero point motion in the harmonic approximation, we…

Materials Science · Physics 2015-05-20 Jeffrey M. McMahon , David M. Ceperley

Two-dimensional fullerene networks have been synthesized in several forms [Hou et al., Nature 606, 507 (2022)], and it is unknown which monolayer form is stable at ambient condition. Using first principles calculations, I show that the…

Materials Science · Physics 2023-10-27 Bo Peng

A molecular solid C$_{50}$Cl$_{10}$ with possible crystalline structures, including the hexagonal-close-packed (hcp) phase, the face-centered cubic (fcc) phase, and a hexagonal monolayer, is predicted in terms of first-principles…

Materials Science · Physics 2009-11-11 Qing-Bo Yan , Qing-Rong Zheng , Gang Su

The crystal structure of solid oxygen at low temperatures and at pressures up to 7 GPa is studied by theoretical calculations. In the calculations, the adiabatic potential of the crystal is approximated by a superposition of pair-potentials…

Materials Science · Physics 2009-11-13 Kazuki Nozawa , Nobuyuki Shima , Kenji Makoshi

Quantum nuclear zero-point motions in solid H$_2$ and D$_2$ under pressure are investigated at 80 K up to 160 GPa by first-principles path-integral molecular dynamics calculations. Molecular orientations are well-defined in phase II of…

Materials Science · Physics 2015-06-05 Grégory Geneste , Marc Torrent , François Bottin , Paul Loubeyre

Crystal structure searching and ab initio calculations have been used here to explore low-energy structures of boron carbides under high pressure. Under pressures of 85-110 GPa, a metastable B6C with R-3m symmetry is found to be…

Materials Science · Physics 2018-01-01 Kang Xia , Mengdong Ma , Cong Liu , Hao Gao , Qun Chen , Julong He , Jian Sun , Hui-Tian Wang , Yongjun Tian , Dingyu Xing

We use the diffusion quantum Monte Carlo to revisit the enthalpy-pressure phase diagram of the various products from the different proposed decompositions of H$_2$S at pressures above 150~GPa. Our results entails a revision of the…

Materials Science · Physics 2017-03-03 Sam Azadi , Thomas D. Kühne

The pressure-induced transformation of diatomic nitrogen into non-molecular polymeric phases may produce potentially useful high-energy-density materials. We combine first-principles calculations with structure searching to predict a new…

Materials Science · Physics 2015-09-30 Yinwei Li , Jian Hao , Hanyu Liu , Siyu Lu , John S. Tse

A calculation of the rotational S$_0$(0) frequencies in high pressure solid para-hydrogen is performed. Convergence of the perturbative series at high density is demonstrated by the calculation of second and third order terms. The results…

Statistical Mechanics · Physics 2009-11-10 Francesco Grazzi , Massimo Moraldi , Lorenzo Ulivi

The first-principle method of mathematical modeling was used to calculate the structural, electronic, phonon, and other characteristics of the normal metallic phase of hydrogen at a pressure of 500 GPa. It has been shown that metal hydrogen…

Superconductivity · Physics 2016-07-06 Nikolay Degtyarenko , Evgeny Mazur