AunXm(n+m=4,X=Cu，Al，Y)混合小团簇的结构和稳定性研究

采用基于密度泛函理论的B3LYP方法，优化了Au_nX_m(n+m=4,X=Cu，A l，Y)二元混合团簇的稳定结构.计算了稳定结构的平均结合能、电离势、电子亲和势、最高占据轨道能级和最低空轨道能级及二者间的能隙.结合Mulliken集居数分析研究了二元混合团簇稳定存在的规律，得出掺杂可以增强团簇稳定性的结论. 关键词： 混合团簇 结合能 能隙 分子轨道集居数     

B$lt;sub$gt;$lt;i$gt;n$lt;/i$gt;$lt;/sub$gt;Y($lt;i$gt;n$lt;/i$gt;=1–11)团簇的结构和电子性质

利用密度泛函理论TPSSh方法对B采用6-311+G(d), 对Y采用Lanl2dz相对论有效势基组, 研究了B_nY (n=1–11)团簇的平均结合能、二阶能量差分、最高分子占据轨道和最低空轨道之间的能级间隙、极化率和第一静态超极化率等物理化学性质. 结果表明, 随着尺寸的增大, B_nY (n=1–11)团簇的最低能量结构从平面逐步演变为立体结构. 随硼原子数n的增加, 团簇的平均结合能表明了较好的热力学稳定性, 有利于Y掺杂B团簇形成较大的块体材料.二阶能量差分表明基态B₃Y, B₅Y和B₇Y团簇较相邻团簇稳定. 能隙表明了基态B₃Y, B₅Y, B₇Y和B₉Y的化学稳定性较高. 综合说明B_nY (n=1–11)硼团簇中, 基态B₃Y, B₅Y和B₇Y具有较好的稳定性. 极化率表明基态B_nY团簇的电子结构随B原子的增加趋于紧凑, 第一静态超极化率表明基态B₅Y, B₄Y, B₃Y和B₆Y平面结构的团簇具有明显的非线性光学性质, 为寻找性能优异的非线性光学材料提供了一定的参考. 关键词： 密度泛函TPSSh方法 nY (n=1–')" href="#">B_nY (n=1– 11)团簇 几何结构 电子性质     

Pd-Y微团簇的结构与性质研究

在相对论有效原子实势近似下，用密度泛函理论方法，对Pd_n(n=2,3,4)，Y_n（n=2,3,4）,Pd_nY(n=1,2,3,4)，PdY_n(n=2,3,4)，Pd₂ Y_n(n=2,3,4)团簇的各种可能的几何构型进行全优化计算,得到它们的基态结构和 光谱性质.结果表明，由于 Jahn-Teller效应， Pd₄和Y₄的基态结 构为C_s构型，P d₃和Y₃为C_2v 构型；混合微团簇Pd₃Y，Pd ₄Y，PdY₃，PdY₄ 和 Pd₂Y₄基态为C_s构型.最后计算了团簇的能级分布和最 高占据轨道与最低空轨道之间的能级间隙,分析了团簇的化学活性. 关键词： Pd-Y团簇 有效原子实势 密度泛函     

密度泛函理论对AunSc3(n=1—7)团簇结构和性质的研究

采用密度泛函理论中的广义梯度近似(GGA)对Au _{n Sc3(n=1—7)团簇的几何构型进行优化,并对能量、频率和电子性质进行了计算.结果表明,与纯金团簇相比,AunSc3 较早出现了立体结构,三角双锥结构的Au2Sc3是AunSc3(n>2)团簇生长的基元;Sc原子的掺杂提高了增强了Au 关键词： n} Sc₃团簇')" href="#">Au_n Sc₃团簇 几何结构 电子性质     

GamPn和GamP-n团簇结构及其光电子能谱的理论研究

采用密度泛函理论中B3LYP泛函方法，在6—31G^*水平上，对Ga_mP_n(m+n≤5)团簇及其阴离子的几何构型和振动光谱性质进行了研究. 在相同水平下计算了Ga_mP^-_n(m+n≤5)的垂直电离能和Ga_mP_n(m+n≤5)的绝热电子亲核势. 结果表明：单线态稳定结构有较高的对称性，二重态的稳定结构对称性相对较低. 关键词： mP_n和Ga_mP^-_n团簇')" href="#">Ga_mP_n和Ga_mP^-_n团簇 密度泛函理论 光电子能谱     

Au_nAg_m~-(n+m=2～4)负离子团簇光脱附电子谱计算

利用密度泛函理论,通过几何优化和态密度计算了Au_nAg_m^-（n+m=2～4）团簇的光电子光谱,结果显示只有Au₂Ag₂^-团簇的第一个峰发生了0.5eV的红移,而其它团簇的峰位置符合的很好,因此理论计算给出的团簇结构是合理的.     

(OsnN)0,±(n=1-6)团簇电子结构与光谱性质的理论研究

采用密度泛函理论中的杂化密度泛函B3LYP方法在赝势基组LANL2DZ水平上对Os_nN^0,±(n=1-6)团簇的各种可能构型进行了几何结构优化,得出了它们的基态构型,并对基态结构的磁学性质、自然键轨道(NBO)、光谱和芳香性进行了理论研究. 研究结果表明:OsN^-和Os₅N^-团簇发生了"磁矩猝灭"的现象,在Os₂N和Os₄N< 关键词： nN^0,±(n=1-6)团簇')" href="#">Os_nN^0,±(n=1-6)团簇 电子结构 光谱性质 密度泛函理论     

GanN－m阴离子团簇的结构及稳定性的研究

利用密度泛函理论(DFT)对Ga_nN^-(n=2—8)和Ga_nN^-₂ (n=1—7)阴离子团簇的结构及稳定性进行了研究.在B3LYP/6-31G^*水平上进行了结构优化和频率分析，得到了Ga_nN^-(n=2—8)和Ga_nN^-₂(n=1—7)阴离子团簇的基态结构.在这些团簇中，原子总数小于等于6的团簇的几何结构为平面结构，原子总数大于6的团簇的几何结构为立体结构；在所研究的团簇中，Ga₄N^-，Ga₆N^-,Ga₄N^-₂和Ga₅N^-₂的基态结构较稳定. 关键词： nN^-_m团簇')" href="#">Ga_nN^-_m团簇 密度泛函理论(DFT) 几何结构     

密度泛函理论研究Hg与Auqn(n=1—6, q=0,+1,-1) 团簇的相互作用

采用密度泛函理论中的广义梯度近似对Hg与小团簇Au ^q_n (n=1—6, q=0, +1, -1)的相互作用进行了系统研究. 结果表明,除Au₅^+,-团簇外,前线分子轨道理论可以成功预测大部分Au _n Hg ^q 复合物的最低能量结构. Au_n团簇对Hg的吸附受团簇尺寸大小和团簇所携带电荷的影 关键词： 密度泛函理论 汞 金团簇 吸附能     

钇小团簇的结构和电离势的计算

采用密度泛函DFT中的B3LYP方法，选择LANL2DZ双ζ基组，优化并得到了Y_n=(n=2—8)小团簇的基态平衡结构，同时计算出其电离势.结果表明，钇原子之间形成团簇最稳定的结构是倾向于平均配位数最大，其电离势没有“奇-偶”振荡或“幻数”效应，表明Y_n团簇光致电离开始主要发生在Y原子局域化的4d轨道上的电子而不是在5s上.对Tomasz提出的钇团簇电离势的解析式进行合理地修正，修正后电离势解析式的计算值与实验值更接近. 关键词： Y团簇 密度泛函 平衡几何结构 电离势     

Geometric,stable and electronic properties of Aun-2Y2（n=3-8） clusters

Employing first-principles methods,based on the density function theory,and using the LANL2DZ basis sets,the ground-state geometric,the stable and the electronic properties of Aun-2Y2 clusters are investigated in this paper.Meanwhile,the differences in property among pure gold clusters,pure yttrium clusters,gold clusters doped with one yttrium atom,and gold clusters doped with two yttrium atoms are studied.We find that when gold clusters are doped by two yttrium atoms,the odd-even oscillatory behaviours of Aun-1Y and Aun disappear.The properties of Aun-2Y2 clusters are close to those of pure yttrium clusters.     

Structural,electronic and magnetic properties of Au<Subscript>n</Subscript>Pt (n = 1−12) clusters in comparison with corresponding pure Au<Subscript>n+1</Subscript> (n = 1−12) clusters

An all-electron scalar relativistic calculation on Au _n Pt (n = 1−12) clusters has been performed by using density functional theory with the generalized gradient approximation at PW91 level. Our results reveal that all the lowest energy geometries of Au _n Pt  (n = 1−12) clusters may be generated by substituting Pt atom for one gold atom of the Au _n+1 cluster at the highest coordinated site. Compared with corresponding pure Au _n+1 cluster, the lowest energy geometries of Au _n Pt clusters are distorted slightly and still keep the planar structures due to the strong scalar relativistic effect in small gold cluster. The Au-Pt bonds are stronger and most Au-Au bonds far from Pt atom are weaker than the corresponding Au-Au bonds in pure Au _n+1 cluster. By substituting Pt atom for one gold atom of Au _n+1 cluster at the highest coordinated site, the relatively stable and inactive odd-numbered Au _n+1 cluster becomes the relatively unstable and reactive odd-numbered Au _n Pt cluster, and the relatively unstable and reactive even-numbered Au _n+1 cluster becomes the relatively stable and inactive even-numbered Au _n Pt  cluster chemically and electronically. All the Au _n Pt clusters prefer low spin multiplicity. The even-numbered Au _n Pt clusters are found to exhibit zero magnetic moment and the odd-numbered Au _n Pt clusters are found to possess magnetic moment with the value of 1 μ _B. The odd-even alterations of magnetic moments and electronic configurations for Au _n Pt clusters are very obvious and may be simply understood in terms of the electron pairing effect.     

Probing the structural and electronic properties of cationic rubidium–gold clusters: [AunRb]+ (n = 1–10)

Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [Au_nRb]⁺ and Au_{n + 1}⁺ (n = 1–10) clusters. For the lowest energy structures of [Au_nRb]⁺ clusters, the planar to three-dimensional transformation is found to occur at cluster size n = 4 and the Rb atoms prefer being located at the most highly coordinated position. The trends of the averaged atomic binding energies, fragmentation energies, second-order difference of energies, and energy gaps show pronounced even–odd alternations. It indicated that the clusters containing odd number of atoms maintain greater stability than the clusters in the vicinity. In particular, the [Au₆Rb]⁺ clusters are the most stable isomer for [Au_nRb]⁺ clusters in the region of n = 1–10. The charges in [Au_nRb]⁺ clusters transfer from the Rb atoms to Au_n host. Density of states revealed that the Au-5d, Au-5p, and Rb-4p orbitals hardly participated in bonding. In addition, it is found that the most favourable channel of the [Au_nRb]⁺ clusters is Rb⁺ cation ejection. The electronic localisation function (ELF) analysis of the [Au_nRb]⁺ clusters shown that strong interactions are not revealed in this study.     

Decay pathways of small gold clusters

The decay pathway competition between monomer and dimer evaporation of photoexcited cluster ions Au ⁺ _n, n = 2-27, has been investigated by photodissociation of size-selected gold clusters stored in a Penning trap. For n > 6 the two decay pathways are distinguished by their experimental signature in time-resolved measurements of the dissociation. For the smaller clusters, simple fragment spectra were used. As in the case of the other copper-group elements, even-numbered gold cluster ions decay exclusively by monomer evaporation, irrespective of their size. For small odd-size gold clusters, dimer evaporation is a competitive alternative, and the smaller the odd-sized clusters, the more likely they decay by dimer evaporation. In this respect, Au ⁺ ₉ shows an anomalous behavior, as it is less likely to evaporate dimers than its two odd-numbered neighbors, Au ⁺ ₇ and Au ⁺ ₁₁. This nonamer anomaly is typical for copper-group cluster ions M ⁺ ₉ (M = Cu, Ag, Au) and a similar behavior is found in the anionic heptamers M ^- ₇. It is discussed in terms of the well-known electronic shell closing at n _e = 8 atomic valence electrons. Received 2 November 2000     

Sputtering of neutral clusters from silver-gold alloys

Polycrystalline Ag, Ag₂₀Au₈₀, Ag₄₀Au₆₀, Ag₈₀Au₂₀ and Au samples were bombarded with 15 keV Ar⁺ at 60° incidence and the resulting secondary neutral yield distribution was studied by non-resonant laser postionisation mass spectrometry. Neutral clusters containing up to 21 atoms were observed for the targets. The yield of neutral clusters, Ag_mAu_n−m, containing n atoms, Y_n, was found to follow a power in n, i.e. Y_n ∝ n^−δ, where the exponent δ varied from 3.2 to 4.0. For a fixed n, the cluster yields showed a variation with number of gold atoms similar to that expected for a binomial distribution. In addition, the cluster compositions from the sputtered alloys were indicative of sputtering from a gold rich surface.     

Geometries, stabilities, and electronic properties of Be-doped gold clusters: a density functional theory study

We have systematically investigated the geometrical structures, relative stabilities and electronic properties of small bimetallic AunBe (n = 1, 2, . . . , 8) clusters using a density functional method at BP86 level. The optimized geometries reveal that the impurity beryllium atom dramatically affects the structures of the Aun clusters. The averaged binding energies, fragmentation energies, second-order difference of energies, the highest occupied-lowest unoccupied molecular orbital energy gaps and chemical hardness are investigated. All of them exhibit a pronounced odd-even alternation, manifesting that the clusters with even number of gold atoms possess relatively higher stabilities. Especially, the linear Au2Be cluster is magic cluster with the most stable chemical stability. According to the natural population analysis, it is found that charge-transferring direction between Au atom and Be atom changes at the size of n = 4.     

Geometrical, electronic, and magnetic properties of small AunSc (n=1-8) clusters

Geometrical, electronic, and magnetic properties of the Sc-doped gold clusters, Au_nSc (n=1-8), have been studied using the density-functional theory within the generalized gradient approximation. An extensive structural search shows that the Sc atom in low-energy Au_nSc isomers tends to occupy the most highly coordinated position. The substitution of a Sc atom for an Au atom in the Au_n+1 cluster markedly changes the structure of the host cluster. Moreover, we confirm that the ground-state Au₆Sc cluster has a distortion to a lower D_2h symmetry. The relative stabilities and electronic properties of the lowest-energy Au_nSc clusters are analyzed based on the averaged binding energies, second-order energy differences, fragmentation energies, chemical hardnesses, and HOMO-LUMO gaps. It is found that the magic Au₃Sc cluster can be perceived as a superatom with high chemical stability and its HOMO-LUMO gap is larger than that of the closed-shell Zr@Au₁₄ cluster. The high symmetry and spin multiplicity of the Au₃Sc and Au₆Sc clusters are responsible for their large vertical ionization potential and electron affinity. The magnetism calculations indicate that the magnetic moment of the Sc atom in the ground-state Au_nSc (n=2-8) clusters gradually decreases for even n and is completely quenched for odd n.     

Insights into the structures,stabilities, electronic and magnetic properties of X2Aun (X = La,Y, and Sc; n = 1–9) clusters: comparison with pure gold clusters

A systematic study of the X₂Au_n (X = La, Y, Sc; n = 1–9) clusters are performed by using the density functional theory at TPSS level. The structures, stabilities, electronic, and magnetic properties are investigated in comparison with pure gold clusters. The results show that the transition points of the doped clusters from two-dimensional to three-dimensional structure are obviously earlier than gold clusters. The impurity X atoms tend to occupy the most highly coordinated position and form the largest probable number of bonds with gold atoms. In addition, the impurity atoms can strongly enhance the stabilities of gold clusters. It indicates that the impurity atoms dramatically affect the geometries and stabilities of the Au_n clusters. The highest occupied molecular orbital–lowest occupied molecular orbital gap, vertical ionisation potential, and chemical hardness show that the X₂Au₆ clusters have higher stabilities than the others. In La₂Au_1–9, Y₂Au_1–7, and Sc₂Au_1–4 clusters, the charges transfer from X atoms to the Au_n frames. The total magnetic moments of X₂Au_n clusters exist distinctly odd–even alternation behaviours except for La₂Au₄ and Sc₂Au₄ clusters.     

Structural,electronic and magnetic properties of gold cluster doped with calcium: Au n Ca (n = 1–8)

The geometrical structures, relative stabilities, electronic and magnetic properties of calcium-doped gold clusters Au _n Ca (n?=?1–8) have been systematically investigated by employing density functional method at the BP86 level. The optimised geometries show that the ground-state structures are planar structures for Au _n Ca (n?=?3–8) clusters. Ca-substituted Au _{n +1} clusters, as well as Au-capped Au _{n ?1}Ca clusters, are dominant growth patterns for the Au _n Ca clusters. The relative stabilities of Au _n Ca clusters for the ground-state structures are analysed based on the averaged binding energies, fragmentation energies and second-order difference of energies. The calculated results reveal that the Au₂Ca isomer is the most stable structure for small size Au _n Ca (n?=?1–8) clusters. The HOMO-LUMO energy gaps as a function of the cluster size exhibit a pronounced even–odd alternation phenomenon. Subsequently, charge transfers and magnetic moment of Au _n Ca (n?=?1–8) clusters have been analysed further.     

Interaction of gold and silver cluster cations with CH<Subscript>3</Subscript>Br: thermal and photoinduced reaction pathways

The reactions of free, size selected Au _n ⁺ (n = 1–3, 5, 7) and Ag₃ ⁺ clusters with CH₃Br as well as the photodissociation of the resulting complexes at 266 nm were studied in a radio frequency ion trap under multiple collision conditions. CH₃Br was found to interact more strongly with the gold clusters than with the silver clusters. All investigated metal clusters exhibited characteristic size dependent adsorbate coverages. Furthermore, the successive loss of methyl radicals was identified as a major thermal reaction channel of the adsorbed CH₃Br molecules. Photodissociation experiments were performed with the product complexes of the trimer clusters and revealed the strongly preferred light-induced fragmentation of Au₃Br₃ ⁺ and Ag₃Br₃ ⁺, respectively, over any other thermal reaction products. However, whereas in the case of the gold cluster complexes the bare Au₃ ⁺ was exclusively re-formed through laser irradiation, considerable photoinduced metal cluster fragmentation occurred in the case of Ag₃Br₃ ⁺.