A combination of state-of-the-art theoretical methods has been used to obtain an atomic-level picture of classical and quantum ordering of protons in cold high-pressure solid hydro-gen. We focus mostly on phases II and III of hydrogen, exploring the effects of quantum nuclear motion on certain features of these phases (through a number of ab initio path-integral molecular dynamics (PIMD) simulations at particular points on the phase diagram). We also examine the importance of van der Waals forces in this system by performing calculations using the optB88-vdW density functional, which accounts for non-local correlations. Our calculations reveal that the transition between phases I and II is strongly quantum in nature, resulting from a competition between anisotropic inter-molecular interactions that restrict molecular rotation and thermal plus quantum fluctuations of the nuclear positions that facilitate it. The transition from phase II to III is more classical because quantum nuclear motion plays only a secondary role and the transition is determined primarily by the underlying potential energy surface. A structure of P21c symmetry with 24 atoms in the primitive unit cell is found to be stable when anharmonic quantum nuclear vibrational motion is included at finite temperatures using the PIMD method. This structure gives a good account of the infra-red (IR) and Raman vibron frequencies of phase II. We find ad-ditional support for C2/c structure as a strong candidate for phase III, since it remains transparent up to 300 GPa, even when quantum nuclear effects are included. Finally, we find that accounting for van der Waals forces improves the agreement between experiment and theory for the parts of the phase diagram considered, when compared to previous work which employed the widely-used Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional.
Hydrogen ordering influence on the proton spin-lattice relaxation time in metal-hydrogen compoun Hydrogen ordering influence on the proton spin-lattice relaxation time in metal-hydrogen compounds
Dual quantum locking: Dynamic coupling of hydrogen and water sublattices in hydrogen filled ice
Sorbonne Université, CNRS UMR 7590, MNHN（索邦大学）；Laboratory of Quantum Magnetism, Institute of Physics, École Polytechnique Fédéerale de Lausanne（洛桑联邦理工学院物理研究所量子磁学实验室）；Dipartimento di Fisica, Sapienza Università di Roma（罗马大学物理系）；Laboratoire pour l’Utilisation des Lasers Intenses (LULI), École Polytechnique（巴黎综合理工学院强激光利用实验室）；Institut Laue-Langevin（朗之万研究所）
First-principles study of the charge ordered phase in $κ$-D$_3$(Cat-EDT-TTF/ST)$_2$: Stability of $π$-electron deuterium coupled ordering in hydrogen-bonded molecular conductors
High-pressure phase stability and superconductivity in La-Zr-H hydrides
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences（中国科学院金属研究所沈阳材料科学国家实验室）；School of Materials Science and Engineering, University of Science and Technology of China（中国科学技术大学材料科学与工程学院）；Skolkovo Institute of Science and Technology（斯科尔科沃科学与技术学院）；Department of Computer Science, Xinzhou Normal University（忻州师范学院计算机系）
Hydrogen uptake and hydride formation in Al$_x$CoCrFeNi high-entropy alloys: First-principles, universal-potential, and experimental study
Ruhr-Universität Bochum（波鸿鲁尔大学）；Max-Planck-Institut for Sustainable Materials（马克斯·普朗克可持续材料研究所）；University of Stuttgart（斯图加特大学）；Deutsches Elektronen-Synchrotron DESY（德国电子同步辐射中心）；Goethe University Frankfurt（法兰克福歌德大学）；Federal Institute for Materials Research and Testing (BAM)（联邦材料研究与测试研究所）
Machine Learning Potentials for Hydrogen Absorption in TiCr$_2$ Laves Phases
Institute for Materials Science, University of Stuttgart（斯图加特大学材料科学研究所）；Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum（波鸿鲁尔大学跨学科先进材料模拟中心 (ICAMS)）
Structural phase stability, electronic structure, magnetic properties and chemical bonding analysis of transition metal ammine borohydrides with amphoteric hydrogen for hydrogen storage
Charge doping induced phase transitions in hydrogenated and fluorinated graphene
我们发现，电荷掺杂可以诱导氢化和氟化石墨烯中三种不同的吸附物相之间的转变。通过结合从头算，近似密度泛函理论和紧束缚计算，我们确定了过渡从岛的C $_8$ H $_2$和C $_8$ F $_2$的随机吸附分布周围的掺杂水平$\pm 0.05$ e/C-原子。此外，在具有随机吸附物覆盖的情况下，电荷掺杂被示出为触发有序转变，其中当掺杂水平超过吸附物浓度时，亚晶格对称性自发地被破坏。再杂化能和晶格畸变能使得仅从一侧共价官能化的石墨烯最容易发生这两种相变。与聚集和有序转变相关的能量增益超过室温热能。
muT2-NMR: Micro-Scale Correlation Relaxometry for in-situ High-Pressure Nuclear Magnetic Resonance
Shanghai Key Laboratory MFree, Institute for Shanghai Advanced Research in Physical Sciences（上海先进物理科学研究院）；Center for High-Pressure Science and Technology Advance Research（高压科学与技术前沿研究中心）；School of Earth and Space Sciences, Peking University（北京大学地球与空间科学学院）
Correct and accurate polymorphic energy ordering of transition-metal monoxides obtained from semilocal and onsite-hybrid exchange-correlation approximations
Ab initio simulation of the first-order proton-ordering transition in water ice
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physics, Renmin University of China（中国人民大学物理学院）
本研究通过结合机器学习势能函数与冰规则保持的更新方法，实现了水冰中首次级质子有序转变的从头计算模拟，揭示了 83 K 处的转变特征并估计核量子效应将转变温度降至 72 K。
Topotactic phase transformation in correlated vanadium dioxide through oxygen vacancy ordering
Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & School of Chemistry and Materials Science, Shanxi Normal University（山西师范大学化学与材料科学学院、教育部磁性分子与磁性信息材料重点实验室）；Research Institute of Materials Science, Shanxi Key Laboratory of Advanced Magnetic Materials and Devices, Shanxi Normal University（山西师范大学材料科学研究所、山西省先进磁性材料与器件重点实验室）
Structural, hydrogen bonding and dipolar properties of alkyl imidazolium-based ionic liquids: a classical and first-principles molecular dynamics study
