相关论文: Simulating Raman Spectra using molecular dynamics,…

We present and evaluate an efficient method for simulating Raman spectra from molecular dynamics (MD) calculations {\it without} defining normal modes. We apply the method to high pressure hydrogen in the high-temperature "Phase IV": a…

A vast amount of Raman spectroscopic data, obtained using diamond anvil cell technique under in situ high pressure-temperature conditions, has been used for mapping the phase transitions of hydrogen in the temperature range of 300 K to 900…

We extend our previous studies on phase IV of solid hydrogen by employing larger cells and k-sampling. We show that uncorrelated hexagonal rotations in the weakly bounded G"-layers are needed to account for the experimentally measured Raman…

The hydrogen phase diagram has a number of unusual features which are generally well reproduced by density functional calculations. Unfortunately, these calculations fail to provide good physical insights into why those features occur. In…

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…

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…

We present extensive molecular dynamics (MD) simulations investigating numerous candidate crystal structures for hydrogen in conditions around the present experimental frontier (400GPa). Spontaneous phase transitions in the simulations…

We have studied solid hydrogen up to pressures of 300 GPa and temperatures of 350 K using density functional theory methods and have found "mixed structures" that are more stable than those predicted earlier. Mixed structures consist of…

Molecular dynamics is a powerful method for studying the behaviour of materials at high temperature. In practice, however, its effectiveness in representing real systems is limited by the accuracy of the forces, finite size effects,…

We report Raman scattering and visible to near-infrared absorption spectra of solid hydrogen under static pressure up to 285 GPa at 85-140 K. We obtain pressure dependences of vibron and phonon modes in agreement with previously determined…

Two new phases of hydrogen have been discovered at room temperature in Ref.1: phase IV above 220 GPa and phase V above ~270 GPa. In the present work we have found a new phase VI at P~360 GPa and T<200 K. This phase is likely metallic as…

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…

Hydrocarbons are of great importance in carbon-bearing fluids in deep Earth and in ice giant planets at extreme pressure (P)-temperature (T) conditions. Raman spectroscopy is a powerful tool to study the chemical speciation of hydrocarbons;…

An unambiguous crystallographic structure solution for the observed phases II-VI of high pressure hydrogen does not exist due to the failure of standard structural probes at extreme pressure. In this work we propose that nuclear magnetic…

The vibrational and structural properties of a hydrogen-rich Group IVa hydride, Ge(CH$_3$)$_4$, are studied by combining Raman spectroscopy and synchrotron X-ray diffraction measurements at room temperature and at pressures up to 30.2 GPa.…

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…

We devise a framework to compute accurate phonons in molecular crystals even in case of strong quantum anharmonicity. Our approach is based on the calculation of the static limit of the phononic Matsubara Green's function from path integral…

The metallic regime of the hydrogen plasma is studied by ab initio Molecular Dynamics simulations, for classical protons and fully degenerate electrons, in the strong coupling regime of the protons. The breakdown of linear screening…

Phase I of hydrogen has several peculiarities. Despite having a close-packed crystal structure, it is less dense than either the low temperature Phase II or the liquid phase. At high pressure, it transforms into either phase III or IV,…

The recent discovery of phase IV of solid hydrogen and deuterium consisting of two alternate layers of graphenelike three-molecule rings and unbound H2 molecules have generated great interests. However, vibrational nature of phase IV…