半哈斯勒化合物XYZ(X=Li,Na, K; Y=Ag,Au; Z=S,Se, Te)拓扑性质的第一性原理研究

利用密度泛函理论和k·p模型方法对半哈斯勒化合物XYZ(X=Li,Na,K;Y=Ag,Au;Z=S,Se,Te)进行了研究．半哈斯勒化合物XYZ可以看作是由Xⁿ⁺离子填充到闪锌矿YZ^n-晶格组成．它们的s态电子形成双重简并Γ₆⁽(2))能带，p-d杂化态形成双重简并Γ₇⁽(2))能带和四重简并Γ₈⁽(4))能带．当s型的Γ₆⁽(2))能带高于Γ₇⁽(2))和Γ₈⁽(4))能带时，化合物为普通绝缘体．然而，当s型Γ₆⁽(2))能带低于Γ₇⁽(2))和Γ₈⁽(4))能带时，化合物是拓扑非平庸绝缘体(如NaAuS)或半金属(如NaAuTe)，这还要取决于负或正...     

Tuning of tetrel bonds interactions by substitution and cooperative effects in XH3Si···NCH···HM (X = H,F, Cl,Br; M = Li,Na, BeH and MgH) complexes

In this work, the interplay between the tetrel bond and the dihydrogen bond is investigated in ternary XH₃Si···NCH···HM complexes, where X = H, F, Cl, Br and M = Li, Na, BeH, MgH. The nature of Si···N and H···H interactions is studied by molecular electrostatic potential (MEP), noncovalent interaction and electron localisation function analyses. All binding distances in the ternary complexes are shorter than those of isolated XH₃Si···NCH and NCH···HM systems. That is, the two types of interactions have a cooperative effect on each other. The results of the MEP analysis indicate that the enhancement of the Si···N and H···H bonds can mainly be attributed to the electrostatic interaction. The plot of the reduced density gradient versus sign (λ₂)ρ indicates that the location of the spike associated with each interaction in the ternary systems moves slightly towards the negative (λ₂)ρ values with respect to the binary systems. This confirms that both Si···N and H···H interactions in the ternary complexes are strengthened by the presence of other. Besides, cooperative effects lead to a considerable change in the ¹⁴N nuclear quadrupole coupling constant values of the ternary complexes relative to the XH₃Si···NCH complexes.     

合成Z=119, 120超重核的理论研究

合成Z=119,120超重核是当今各核物理实验室争相追逐的目标,理论预言可靠的弹靶组合、入射能等信息有助于超重核合成的实验设计和探测。本工作基于双核模型研究影响重离子核反应生成截面大小的反应机制,计算了$^{50}{\rm{Ti}}$+$^{249}{\rm{Bk}}$、$^{50}{\rm{Ti}}$+$^{249}{\rm{Cf}}$两个弹靶组合,预测$^{50}{\rm{Ti}}$+$^{249}{\rm{Bk}}$的生成截面为0.021 1 pb。考虑双核系统熔合与存活两个过程,重点关注$^{52-59}{\rm{Cr}}$+$^{243}{\rm{Am}}$、$^{54-62}{\rm{Mn}}$+$^{243}{\rm{Am}}$、$^{56-72}{\rm{Ni}}$+$^{238}{\rm{U}}$生成截面的同位素链依赖性,研究表明熔合几率随弹核质量数呈现强烈的依赖行为,直接影响蒸发剩余截面大小。     

Enhancement effect of lithium bonding on the strength of pnicogen bonds: XH2P···NCLi···NCY as a working model (X = F,Cl; Y = H,F, Cl,CN)

MP2 calculations with aug-cc-pVDZ basis set were used to analyse intermolecular interactions in XH₂P···NCLi···NCY triads (X = F, Cl; Y = H, F, Cl, CN) which are connected via pnicogen bond and lithium bond. To understand the properties of the systems better, the corresponding dyads are also studied. Molecular geometries and interaction energies of dyads, and triads are investigated at the MP2/aug-cc-pVDZ computational level. Particular attention is paid to parameters such as cooperative energies and many-body interaction energies. All studied complexes, with the simultaneous presence of a lithium bond and a pnicogen bond, show cooperativity with energy values ranging between ?4.73 and ?8.88 kJ mol^?1. A linear correlation was found between the interaction energies and magnitude of the product of most positive and negative electrostatic potentials. According to energy decomposition analysis, it is revealed that the electrostatic interactions are the major source of the attraction in the title complexes.     

The strengthening effect of a hydrogen or lithium bond on the Z···N aerogen bond (Z = Ar,Kr and Xe): a comparative study

An ab initio study is performed on O₃Z···NCM···NCX (Z = Ar, Kr and Xe; M = H and Li; X = H, F and CH₃) complexes to investigate cooperativity effects between aerogen and hydrogen or lithium bonding interactions in these systems. To understand the cooperative effects, a detailed analysis of the binding distances, interaction energies and bonding properties is performed on these complexes. The results indicate that all Z···N and H/Li···N binding distances in the ternary complexes are shorter than those of corresponding binary systems. For a given M or X, cooperative energies increase as Z = Xe > Kr > Ar. Moreover, O₃Z···NCLi···NCX complexes exhibit a larger cooperative energy than O₃Z···NCH···NCX ones. The non-covalent interaction (NCI) index analysis indicates that the formation of an H/Li···N interaction in the ternary complexes shifts the location of the spike associated with the Z···N interaction towards the negative λ₂ρ values. This indicates that NCI analysis can be regarded as a useful tool for the study of cooperative effects between two different non-covalent interactions. Also, cooperative effects in O₃Z···NCM···NCX complexes make a decrease in ¹⁴N nuclear quadrupole coupling constants of NCH or NCLi molecule.     

c=3, N=2 超共形场论的Z2 Orbifold-Prime模型

讨论了二维环面上中心荷c=3, N=2 的超共形场论. 特别给出该理论的配分函数. 进一步,为了产生新的模型,回顾了一般的orbifold方法. 然后构造了模不变的Z2 Orbifold-Prime模型.     

N=Z原子核性质的研究

论述了N=Z核实验和理论研究的历史和现状在,N=Z,是研究T=0对关联最好的核区,实验表明T=0和n-p对关联起着重要的作用,理论研究知心朋友同时包括T=0和T=1的对关联,是研究它们之间竞争及相变。 The history and current status of the study of N=Z nuclei are reviewed. T=0 n p pairing correlation is expected to play an important role in the structure of the nuclei along N=Z line. Both T=0 and T=1 pairing modes should be included in the theoretical models. Phenomena like possible competition and phase transition between different pairing modes are becoming important issues in nuclear structure.     

Cooperativity effects between σ-hole interactions: a theoretical evidence for mutual influence between chalcogen bond and halogen bond interactions in F2S···NCX···NCY complexes (X = F,Cl, Br,I; Y = H,F, OH)

Quantum chemical calculations are performed to study the cooperativity effects between chalcogen bond and halogen bond interactions in F₂S···NCX···NCY complexes, where X = F, Cl, Br, I and Y = H, F, OH. These effects are investigated in terms of geometric and energetic features of the complexes, which are computed by second-order Møller–Plesset perturbation theory (MP2). For each F₂S···NCX···NCY complex studied, the effect of cooperativity on the chalcogen bond is dependent on the strength of halogen bond. The results indicate that the interaction energies of chalcogen and halogen bonds in the triads are more negative relative to the respective dyads. The interaction energy of chalcogen bond is increased by 31%–49%, whereas that of halogen bond by 28%–62%. The energy decomposition analysis reveals that electrostatic force plays a main role in the cooperativity effects between the chalcogen bond and halogen bond interactions. The topological analysis, based on the quantum theory of atoms in molecules, is used to characterise the interactions and analyse their enhancement with varying electron density at bond critical points.     

Magnetic Properties of Hydrides of RNi1 – xSix Compounds (R = Dy,Gd, x = 0.05, 0.02)

Physics of the Solid State - The magnetic properties of intermetallic compounds GdNi0.98Si0.02 and DyNi0.95Si0.05 and hydrides based on them have been studied. It is found that a partial...     

Structure and stability of AgXen Z({\sf n=1}–3, {\sf Z=-1}, 0, +1) clusters. Theoretical insights

The structure and stability of AgXe_n ^Z(n=1–3, Z=-1, 0, +1) cluster series at CCSD(T) theoretical level have been investigated. It is shown that the cations are more stable and have more compact geometries than the anions and neutrals. The role of the interaction was explained using the natural bond orbital (NBO) analysis.     

38≤Z≤42类钴离子n=3,△n=0跃迁的理论计算

用多组态自洽场方法,结合作提出的半经验拟合公式,首先对３８≤Ｚ≤４２类钴离子３ｐ＾６３ｄ＾９,３ｐ＾５３ｄ＾１０,３ｐ＾６３ｄ＾８４ｐ组态的能级进行计算,然后根据能级值算出相应的电偶极跃迁的谱线波长,并给出各谱线的ＨＦＲ振子强度。     

Vibrational properties of Cu<Subscript>3</Subscript>XY<Subscript>4</Subscript> sulvanites (X = Nb,Ta, and V; and Y = S,and Se) by ab initio molecular dynamics

In this work, we present a structural and dynamic characterisation of six different types of sulvanites Cu₃ X Y ₄ with X = Nb, V and Ta, and Y = S and Se. These materials have been the subject of intense study in recent times primarily as potential candidates for solar cell devices, as well as for their enhanced opto-electrical properties. Here, by means of first-principles calculations, we study the structural and dynamic behaviour of these materials at different temperatures, which is important for use of these materials in high-temperature conditions. In this work the dynamic and structural properties are studied using the Density Functional Theory technique. The simulations were performed at four different temperatures, ranging from room temperature to ~1500 K. By using first-principles molecular dynamics in the microcanonical ensemble, we are able to determine the vibrational spectra of these sulvanites. With this information we report for the first time the partial vibrational density of states of these structures at different temperatures. With these results we determine the vibrational properties of the basic building blocks of those sulvanites and their dynamic behaviour under temperature effects. We also show that the building blocks that which make up these structures, remain stable as the temperature increases.     

重费米子化合物 CemMnIn3m+2n(m = 1, 2, 3; n = 0, 1, 2; M = Co,Rh,Ir,Pt 及Pd) 的角分辨光电子能谱研究

重费米子材料以其新奇多变的宏观性质,复杂而难以理解的微观物理过程而受到广泛的关注,长期是凝聚态物理研究的重点。角分辨光电子能谱作为一种能够直接探测材料电子结构的实验手段,随着近年来实验技术的高度发展,能量和动量分辨率得到了极大的提高,能够有力地探测到强关联材料中更加精细的电子结构。使用角分辨光电子能谱探测重费米子材料的电子结构,为理解其各种物理过程提供强有力的实验证据,进而推进重费米子理论的发展。本文回顾 Ce 基重费米子材料 CemMnIn3m+2n (m = 1; 2; 3;n = 0; 1; 2;M =Co, Rh, Ir, Pt, Pd) 系列化合物的角分辨光电子能谱研究,包括电子结构的维度、近藤共振、f 电子与导带电子的杂化和电子结构随温度的变化等。     

Possible Way to Synthesize Superheavy Element Z=117

Within the framework of the dinuclear system model, the production of superheavy element Z = 117 in possible projectile-target combinations is analysed systematically. The calculated results show that the production cross sections are strongly dependent on the reaction systems. Optimal combinations, corresponding excitation energies and evaporation channels are proposed, such as the isotopes^248.249 Bk in ^48 Ca induced reactions in 3n evaporation channels and the reactions ^45Sc＋246.248Cm in 3n and 4n channels, and the system ^51 V＋ 244pu in 3n channel.     

Blue and red shifts in Rg···HCN and Rg···HNC complexes (Rg=He,Ne, Ar,Kr)

The shift in the harmonic vibrational frequency of the H–C stretch of HCN on formation of the linear Rg···HCN complexes, and of the H–N stretch of HNC on the formation of Rg···HNC complexes (Rg?=?He, Ne, Ar, Kr), has been determined by ab initio computations. These shifts are in agreement with predictions from a model based on perturbation theory and involving the first and second derivatives of the interaction energy with respect to displacement of the H–C (H–N) bond length from its equilibrium value in the monomer. Small blue shifts were obtained for He···HCN, Ne···HCN and He···HNC, while red shifts were obtained for the other weakly bound complexes. These vibrational characteristics are rationalized by considering the balance between the interaction energy derivatives obtained from the perturbative model. For all complexes, the IR intensity of the H–C or H–N stretch was increased from the isolated monomer values on complexation.     

丰中子Z=96—102同位素链的N=184闭壳

在相对论平均场理论框架下, 首先证明了对力强度存在明显的壳效应, 然后用此方法研究了Z=96—102区域内超重同位素链中中子壳封闭问题, 证明了在超重元素中,N=184处确实存在壳封闭. 并据此给出了一种检验壳封闭的新方法.     

围绕Z=56和N=88丰中子核区八极形变的研究

介绍了通过测量重核裂变产生的瞬发γ谱方法,对围绕Ｚ＝５６、Ｎ＝８８丰中子核区高自旋态八极形变的研究,并对Ｘｅ、Ｂａ、Ｃｅ和Ｌａ等丰中子核链的八极形变特性进行了讨Through study of the prompt γ rays in spontaneous fission, the octupole deformation in neutron rich Xe, Ba, Ce and La isotopes around Z =56, N =88 region was assigned. The properties of the octupole deformation in these nuclei were also discussed. 论．     

A theoretical analysis of the weakly bound complexes HM ··· HXY (M=O and S; XY=CN and NC): comparison with H2M ··· HXY complexes

An ab initio study of the complexes formed between MH (M=O and S) and HXY (XY=CN and NC) was carried out at the UQCISD/6-311++G(2df,2p) level. For comparison, the corresponding H₂M–HXY complexes were also studied. Two minima were found for each molecular pair. The results show the necessity of electron correlation and larger basis sets in the study of open-shell hydrogen-bonded complexes. As the proton donor and acceptor, the OH radical is favourable for the formation of a hydrogen bond with HXY than is the SH radical. The MH radical is more likely to donate a proton than H₂M, whereas H₂M is more likely to accept a proton than the MH radical. Natural bond orbital and atoms in molecules analyses were performed for these systems. It is shown that the complexes are held together mainly by electrostatic interactions.