Sequestration of helium and xenon via iron-halide compounds in early Earth

The terrestrial abundance anomalies of helium and xenon suggest the presence of deep-Earth reservoirs of these elements,which has led to great interest in searching for materials that can host these usually unreactive elements.Here,using an advanced crystal structure search approach in conjunction with first-principles calculations,we show that several Xe/He-bearing iron halides are thermodynamically stable in a broad region of P–T phase space below 60 GPa.Our results present a compelling case for sequestration of He and Xe in the early Earth and may suggest their much wider distribution in the present Earth than previously believed.These findings offer insights into key material-based and physical mechanisms for elucidating major geological phenomena.

Theory-orientated discovery of high-temperature superconductors in superhydrides stabilized under high pressure

A dream long held by physicists has been to raise the critical temperature(Tc)—the temperature below which the material exhibits no electrical resistance—of a superconductor to room temperature.The most recent excitement in that regard has centered on rare-earth superhydrides,of which LaH10 at 190 GPa has a remarkably high Tc of 260 K.

Superconductivity in Shear Strained Semiconductors

Semiconductivity and superconductivity are remarkable quantum phenomena that have immense impact on science and technology,and materials that can be tuned,usually by pressure or doping,to host both types of quantum states are of great fundamental and practical significance.Here we show by first-principles calculations a distinct route for tuning semiconductors into superconductors by diverse large-range elastic shear strains,as demonstrated in exemplary cases of silicon and silicon carbide.Analysis of strain driven evolution of bonding structure,electronic states,lattice vibration,and electron-phonon coupling unveils robust pervading deformation induced mechanisms auspicious for modulating semiconducting and superconducting states under versatile material conditions.This finding opens vast untapped structural configurations for rational exploration of tunable emergence and transition of these intricate quantum phenomena in a broad range of materials.

Cloning of Ln Gene Through Combined Approach of Map-based Cloning and Association Study in Soybean

Increasing yield is one of the most important goals in crop breeding. Soybean （Glycine max L. Merr.）, one of the most economically important leguminous seed crops, provides the majority of plant proteins, and more than a quarter of the world＇s food and animal feed （Graham and Vance, 2003）. The yield of soybean is finally determined by the number of seeds per unit area, which affected by many characters, such as height, branching number, photosynthesis, seed size, seed number. The number of seeds per pod is taken for one of the critical components that related to yield （You et al., 1995）.

An automated predictor for identifying transition states in solids

The minimum energy path(MEP)and transition state are two key parameters in the investigation of the mechanisms of chemical reactions and structural phase transformations.However,determination of transition paths in solids is challenging.Here,we present an evolutionary method to search for the lowest energy path and the transition state for pressure-induced structural transformations in solids without any user input or prior knowledge of possible paths.Instead,the initial paths are chosen stochastically by connecting randomly selected atoms from the initial to final structure.The MEP of these trials paths were computed and ranked in order of their energies.The matrix particle swarm optimization algorithm is then used to generate improved transition paths.The procedure is repeated until the lowest energy MEP is found.This method is validated by reproducing results of several known systems.The new method also successfully located the MEP for the direct low-temperature pressure induced transformation of face centered-cubic(FCC)silicon to the simple hexagonal(sh)phase and FCC lithium to a complex body centered-cubic cI16 high-pressure phase.The proposed method provides a convenient,robust,and reliable approach to identify the MEP of phase transformations.The method is general and applicable to a variety of problems requiring the location of the transition state.

Interface structure prediction via CALYPSO method

The atomistic structures of solid–solid interfaces are of fundamental interests for understanding physical properties of interfacial materials. However, determination of interface structures faces a substantial challenge, both experimentally and theoretically. Here, we propose an efficient method for predicting interface structures via the generalization of our in-house developed CALYPSO method for structure prediction. We devised a lattice match toolkit that allows us to automatically search for the optimal latticematched superlattice for construction of the interface structures. In addition, bonding constraints(e.g.,constraints on interatomic distances and coordination numbers of atoms) are imposed to generate better starting interface structures by taking advantages of the known bonding environment derived from the stable bulk phases. The interface structures evolve by following interfacially confined swarm intelligence algorithm, which is known to be efficient for exploration of potential energy surface. The method was validated by correctly predicting a number of known interface structures with only given information of two parent solids. The application of the developed method leads to prediction of two unknown grain boundary(GB) structures(r-GB and p-GB) of rutile TiO_2 ∑5(2 1 0) under an O reducing atmosphere that contained Ti^(3+)as the result of O defects. Further calculations revealed that the intrinsic band gap of p-GB is reduced to 0.7 eV owing to substantial broadening of the Ti-3 d interfacial levels from Ti^(3+)centers.Our results demonstrated that introduction of grain boundaries is an effective strategy to engineer the electronic properties and thus enhance the visible-light photoactivity of TiO_2.

高压下稳定的S_(3)O_(4):“硫过量”问题的启示

人们发现火山喷发释放出的硫含量比前期估测火山喷发溶体中所容纳的硫高出了几个数量级,这就是火山喷发的“硫过量”问题.经过多年的研究,关于过量硫的来源问题人们提出了多种可能,但仍是一个谜团.本工作利用自主发展的CALYPSO晶体结构预测方法结合第一性原理计算,预言了一种新型硫氧化合物S_(3)O_(4).该化合物包含S(+Ⅱ)和S(+Ⅳ)混合价态,并且在79 GPa以上的压力条件下可以稳定存在.第一性原理计算表明,在深地幔的高压条件下,S_(3)O_(4)可以通过硫酸盐和硫化物与铁和针铁矿经氧化还原反应生成,并在地球浅层压力条件下可以分解为SO2和S单质.因此,本工作预言的S_(3)O_(4)是促进含硫矿物分解产生SO2的关键中间化合物.研究工作为解决火山喷发过程中的“硫过量”问题提供了新的思路,同时也为理解地球表面和下地幔深部之间的硫交换提供了重要的理论储备.

Chloroplast DNA Underwent Independent Selection from Nuclear Genes during Soybean Domestication and Improvement

The chloroplast is one of the most important organs in plants because of its essential role in photosynthesis.Studies have shown that the chloroplast was once a free-living cyanobacteria and was integrated into the host species through endosymbiosis（Goksoyr.1967）.after which a large number of its genes had been donated to the host nuclear genome（Heins and Soll, 1998）.

Structure search of two-dimensional systems using CALYPSO methodology

The dimensionality of structures allows materials to be classified into zero-, one-, two-, and threedimensional systems. Two-dimensional (2D) systems have attracted a great deal of attention andtypically include surfaces, interfaces, and layered materials. Due to their varied properties, 2D systemshold promise for applications such as electronics, optoelectronics, magnetronics, and valleytronics.The design of 2D systems is an area of intensive research because of the rapid development of abinitio structure-searching methods. In this paper, we highlight recent research progress on acceleratingthe design of 2D systems using the CALYPSO methodology. Challenges and perspectives for futuredevelopments in 2D structure prediction methods are also presented.

The exotically stoichiometric compounds in Al-S system under high pressure

Aluminum and sulfur,as abundant elements in earth,only form Al_(2)S_(3) in nature at ambient pressure.It has been realized that the stoichiometry of compounds may change under high pressure,which is crucial in the discovery of novel materials.In this work,we systematically perform structure search for Al-S system under pressure.

Predicting the structure and stability of titanium oxide electrides

The search for new inorganic electrides has attracted significant attention due to their potential applications in transparent conductors,battery electrodes,electron emitters,as well as catalysts for chemical synthesis.However,only a few inorganic electrides have been successfully synthesized thus far,limiting the variety of electride examples.Here,we show the stabilization of inorganic electrides in the Ti-rich Ti–O system through first-principles calculations in conjunction with swarm-intelligence-based CALYPSO method for structure prediction.Besides the known Ti-rich stoichiometries of Ti_(2)O,Ti_(3)O,and Ti_(6)O,two hitherto unknown Ti_(4)O and Ti_(5)O stoichiometries are predicted to be thermodynamically stable at certain pressure conditions.We found that these Tirich Ti–O compounds are primarily zero-dimensional electrides with excess electrons confined in the atom-sized lattice voids or between the cationic layers playing the role as anions.The underlying mechanism behind the stabilization of electrides has been rationalized in terms of the excess electrons provided by Ti atoms and their accommodation of excess electrons by multiple cavities and layered atomic packings.The present results provide a viable direction for searching for practical electrides in the technically important Ti–O system.