First-principles calculations for titanium monoxide clusters TinO （n=1-9）

Based on the density-functional theory, this paper studies the geometric and magnetic properties of TinO （n=1-9） clusters. The resulting geometries show that the oxygen atom remains on the surface of clusters and does not change the geometry of Tin significantly. The binding energy, second-order energy differences with the size of clusters show that Ti7O cluster is endowed with special stability. The stability of TinO clusters is validated by the recent time-of-flight mass spectra. The total magnetic moments for TinO clusters with n=1-4, 8-9 are constant with 2 and drop to zero at n=5-7. The local magnetic moment and charge partition of each atom, and the density of states are discussed. The magnetic moment of the TinO is clearly dominated by the localized 3d electrons of Ti atoms while the oxygen atom contributes a very small amount of spin in TinO clusters.     

密度泛函理论研究ScnO(n=1—9)团簇的结构、稳定性与电子性质

采用基于密度泛函理论的BP86/CEP-121G （O原子采用6-311G^**基组）方法,对Sc_nO （n=1—9）团簇的几何结构、能量与稳定性、电子结构性质及其随团簇尺寸的变化趋势进行了研究.随着团簇原子个数的增加,O原子从位于Sc_n团簇结构的边缘转变为占据团簇的内部位置.O原子的掺入增加了Sc_n团簇的稳定性,使其能隙升高,并改变了其稳定性及电子结构性质随团簇尺寸变化的规律;含有偶数个Sc原子的氧化物团簇比其周围邻近的含有奇数个Sc原子的氧化物团簇具有相对较高的稳定性.Sc_nO团簇电离势的理论计算值与实验值符合得较好,而其电子亲和势呈现振荡交替上升的变化趋势;用最大化学硬度规律等方法表征了Sc_nO氧化物团簇的稳定性和电子结构性质. 关键词： nO团簇')" href="#">Sc_nO团簇 几何结构 电子性质 密度泛函理论     

AlO2和Al2O分子的结构与解析势能函数

运用密度泛函理论的B3LYP方法在6-311++G^**水平上,对AlO₂,Al₂O分子的结构进行了优化计算,得到AlO₂,Al₂O分子的稳定结构都为D_∞h构型.　AlO₂电子态为X²Π_u,平衡核间距R_Al-O关键词： 2')" href="#">AlO₂ 2O')" href="#">Al₂O Murrell-Sorbie函数 多体项展式理论     

BenLa (n=1—18) 团簇的结构、电子性质和磁性

采用基于密度泛函理论的第一性原理方法,在多种初始构型下充分考虑自旋多重度,研究了Be_nLa团簇的平衡几何结构、电子性质和磁性.结果表明：Be_nLa团簇的基态附近有许多能量非常接近的同分异构体,说明该团簇结构较复杂,对其基态的寻找极具挑战性.Be_nLa团簇具有磁性且稳定性远高于Be_n+1团簇,由此可知通过选择合适的掺杂元素可能得到高稳定性的磁性团簇.Be_{1 关键词： n}La团簇')" href="#">Be_nLa团簇 平衡几何结构 电子性质和磁性     

An ab initio study of niobium (n = 2--11) clusters: structure, stability and magnetism

The ground-state configurations of the Nbn (n = 2-11) clusters are studied through the first-principles calculations. It is found that niobium clusters (n = 2-11) tend to form compact structures with low symmetry. The clusters with 4, 8 and 10 atoms are found to be magic and have relatively large highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gaps. The Nbn clusters possess low magnetic moments, which exhibit an odd-even oscillational character. The analyses of calculated electronic density and population of the lowest-energy niobium clusters for n = 2, 3, 5, 7, 9, 11 show that the total magnetic moments of Nbn originate mainly from a few Nb atoms with longer spacings between them in most cases, while they are located on two Nb atoms for n = 2, 3, 5. The total magnetic moments come mainly from the 4d local moments but with the exception of the Nb5 cluster.     

基于密度泛函理论的SinCN团簇结构及稳定性的研究

利用密度泛函理论(DFT)中的B3LYP/6-311G*方法,对SinCN(n=2-6)团簇的几何结构、振动频率和基态能量等性质进行了研究,分别讨论了其基态和亚稳态结构的能量及自旋多重态。振动频率和振动强度被用来判断体系的稳定性。结果表明,随着Si原子数的增加,零点振动能、热容量和熵近似线性增长,其平均增幅分别为0.80 kcal/mol、5.20 cal/mol•K和12.72 cal/mol•K。n为偶数的SinCN团簇比m为奇数的更为稳定。     

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     

Density functional study of Al-doped Au clusters

The equilibrium geometries and electronic properties of Au_nAl, up to n=13, have been systematically investigated using the density functional theory. The results show that, for the Au_nAl clusters, two patterns are identified. Pattern one (n=2, 3, 8), the lowest-energy geometries prefer two-dimensional structures. Pattern two (n=4-7, 9--13), the lowest-energy geometries prefer three-dimensional structures. According to the analysis of the binding energy and the fragmentation energy, Au_nAl clusters with odd n are found to be more stable than those with even n. The same trend of alternation can be illuminated according to the computational results in the HOMO--LUMO gap, the ionization potential, and the electron affinities. The Al atom not only changes the structures of pure gold clusters, but also enhances their stabilities. NBO analysis indicates 6s orbital of Au atom hybridizes with 3p orbital of Al atom.     

Appearance of metallic features in small tungsten clusters

The structures and properties of W_n (n=2--14) clusters were studied by using the density functional theory (DFT) at LSDA level. The most stable structures of W_n (n=2--14) clusters with global minimum were determined. The average binding energy (E_b), the first and second difference of total energy (\itδ E, \itδ₂E), the vertical detachment energy (VDE), and the HOMO-LUMO gap versus the size were also discussed. The abrupt decrease of VDE and HOMO-LUMO gap at size n=8 and 10 implied that tungsten clusters of W₈ and W₁₀ appeared to have metallic features. These changes were also accompanied by the delocalization of electron charge density and the strong hybridization between 5d and 6s orbits in W₈ and W_10 clusters. Our results are in good agreement with the available experimental data.     

第一性原理对NaBen(n=1—12)团簇最低能量结构及其电子性质的研究

从第一性原理出发对NaBe_n(n=1—12)团簇的最低能量结构和电子性质进行了研究.结果表明，掺杂原子(Na)导致主团簇Be_n的几何结构发生显著变化；出现了共价键和金属键的成键特性；Na-Be最近邻间距和能隙随着团簇尺寸的增加出现了振荡;n=4是团簇的幻数. 关键词： n团簇')" href="#">NaBe_n团簇 最低能量结构 电子性质     

Density-functional theory study of the geometries,stabilities, and electronic properties of Au n Rb (n = 1–10) clusters: comparison with pure gold clusters

The density functional method with the relativistic effective core potential has been employed to investigate systematically the geometric structures, relative stabilities, growth-pattern behavior, and electronic properties of small bimetallic Au _n Rb (n?=?1–10) and pure gold Au _n (n?≤?11) clusters. For the geometric structures of the Au _n Rb (n?=?1–10) clusters, the dominant growth pattern is for a Rb-substituted Au _{n +1} cluster or one Au atom capped on a Au _{n –1}Rb cluster, and the turnover point from a two-dimensional to a three-dimensional structure occurs at n?=?4. Moreover, the stability of the ground-state structures of these clusters has been examined via an analysis of the average atomic binding energies, fragmentation energies, and the second-order difference of energies as a function of cluster size. The results exhibit a pronounced even–odd alternation phenomenon. The same pronounced even–odd alternations are found for the HOMO–LUMO gap, VIPs, VEAs, and the chemical hardness. In addition, about one electron charge transfers from the Au _n host to the Rb atom in each corresponding Au _n Rb cluster.     

中性和阳离子丁酮团簇的结构及稳定性的理论研究

使用密度泛函B3LYP方法,在6-31G*和6-311+G**基组水平上计算中性和阳离子丁酮团簇(CH_3COC_2H_5)_n和(CH_3COC_2H_5)_n~+(n 7)的稳定结构,并比较不同尺寸团簇之间的相对稳定性.中性和阳离子丁酮团簇的结构具有相似性:n=3—7时,组成团簇的丁酮的平均几何参数基本相同,单环结构最稳定;随着团簇尺寸的增加,双环结构的稳定性逐渐上升.通过平均结合能、一阶差分能、HOMO-LUMO能隙等计算分析可知:在所研究的各种尺寸团簇中,(CH_3COC_2H_5)_3是最稳定的中性团簇,与实验中的最强峰对应;(CH_3COC_2H_5)_4~+是最稳定的阳离子团簇.通过电离能计算得到丁酮分子的垂直电离能为9.535 eV与实验值相符,同时证明中性和阳离子丁酮二元团簇的结构变化较大.研究结果为实验中丁酮团簇碎片离子的形成机理提供一定的理论依据,并且为进一步研究酮类分子团簇的生长规律提供有价值的信息.     

SinC2N团簇结构及稳定性的密度泛函理论研究

利用密度泛函理论(DFT)中的B3LYP/6-311G*方法,对SinC2N(n=2-6)团簇的几何结构、振动频率和基态能量等性质进行了研究,分别讨论了其基态和亚稳态结构的能量及自旋多重态。振动频率和振动强度被用来判断体系的稳定性。结果表明,随着Si原子数的增加,零点振动能、热容量和熵近似线性增长,其平均增幅分别为1.03kcal/mol、4.84cal/mol•K和11.96cal/mol•K。n为奇数的SinC2N团簇比n为偶数的更为稳定。     

SinC2N团簇结构及稳定性的密度泛函理论研究

利用密度泛函理论(DFT)中的B3LYP/6-311G*方法,对SinC2N(n=2-6)团簇的几何结构、振动频率和基态能量等性质进行了研究,分别讨论了其基态和亚稳态结构的能量及自旋多重态。振动频率和振动强度被用来判断体系的稳定性。结果表明,随着Si原子数的增加,零点振动能、热容量和熵近似线性增长,其平均增幅分别为1.03kcal/mol、4.84cal/mol•K和11.96cal/mol•K。n为奇数的SinC2N团簇比n为偶数的更为稳定。     

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.     

First-principles study of structrural and corrected band properties of wurtzite Zn1-xCdxO and Zn1-xMgxO systems

A first-principles method based on density functional theory(DFT),a generalized gradient approximation(GGA),and a projector-augmented wave(PAW) are used to study the structual and band properties of wurtzite Zn1-xCdxO and Zn1-xMgxO(0 ≤x≤1) ternary alloys.By taking into account all of the possible structures,the band gaps of Zn1-xCdxO and Zn1-xMgxO alloys are corrected and compared with experimental data.     

FeBN(N≤6)团簇的结构与磁性

利用密度泛函理论中的广义梯度近似(GGA)，在考虑自旋多重度后，预测了FeB_N(N≤6)团簇的基态结构.结果表明基态团簇的自旋多重度分别为4，3，2，1，2和1，其中FeB₄团簇比较稳定.同时对FeB_N(N≤6)基态团簇的磁性做了系统地研究，发现除了FeB₅团簇外，FeB_N(N≤6)团簇的总磁矩和Fe原子磁矩随团簇尺寸的增大而减小. 关键词： N团簇')" href="#">FeB_N团簇 自旋多重度 磁矩     

The relativistic density functional investigations on geometries, electronic and magnetic properties of Irn (n=1-13) clusters

<正>The Ir_n(n=1-13) clusters are studied using the relativistic density functional method with generalized gradient approximation.A series of low-lying structures with different spin multiplicities have been considered.It is found that all the lowest-energy Ir_n(n=4-13) geometries prefer non-compact structures rather than compact structure growth pattern.And the cube structure is a very stable cell for the lowest-energy Ir_n(n8) clusters.The second-order difference of energy,the vertical ionization potentials,the electron affinities and the atomic average magnetic moments for the lowest-energy Ir_n geometries all show odd-even alternative behaviours.     

Density functional study of Agn-1Y (n=2-10) clusters

Employing the density functional theory, we investigate the lowest-energy geometric, the stable and the electronic properties of Ag_n-1Y (n=2-10) clusters in this paper. The structural optimization and the frequency analysis are performed at the B3LYP/LANL2DZ level. Meanwhile, the differences in geometry, stability and electronic properties between Ag_n and Ag_n-1Y (n=2-10) clusters are also studied. The results show that for the doping of the yttrium atoms, the structures and the average binding lengths of the Ag_n clusters are greatly changed. In addition, the thermodynamic stabilities of the Ag_n clusters are enhanced generally with the doping of the Y atoms. In addition, the chemical stabilities of the Ag_n-1Y clusters are still improved compared with that of the three-dimensional Ag_n clusters.     

Density functional theory study of MgnNi2 (n=1-6) clusters

The geometries of Mg_nNi₂ (n=1-6) clusters are studied by using the hybrid density functional theory (B3LYP) with LANL2DZ basis sets. For the ground-state structures of Mg_nNi₂ clusters, the stabilities and the electronic properties are investigated. The results show that the groundstate structures and symmetries of Mg clusters change greatly due to the Ni atoms. The average binding energies have a growing tendency while the energy gaps have a declining tendency. In addition, the ionization energies exhibit an odd-even oscillation feature. We also conclude that n=3, 5 are the magic numbers of the Mg_nNi₂ clusters. The Mg₃ Ni₂ and Mg₅Ni₂ clusters are more stable than neighbouring clusters, and the Mg₄Ni₂ cluster exhibits a higher chemical activity.