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1.
First-principle study of geometries, electronic structures and vibrational spectra of neutral and anionic onion-like [As@Ni12@As20]
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We present results of first-principle study for both neutral and anionic onion-like [As@Ni12@As20]. The ground-states of singly-charged and doubly-charged anions deviate from ideal Ih symmetrical geometry because of Jahn--Teller effect, whereas the triply-charged singlet and neutral quartet have similar stable geometries of Ih symmetry. The infrared and Raman spectra may provide a way to determine various charge states of this molecule with the same symmetry. Based on our systematical calculations, we suggest additional experimental measurements in order to determine the appropriate functional with great confidence, which should be important in the research for future quantum dot devices. 相似文献
2.
The equilibrium geometries and the atomization energies of Cu_n(n≤9) clusters have been calculated using the B3LYP/LANL2DZ method. It is shown that the clusters do not copy the bulk structures and undergo significant geometrical changes with size and the atomization energy per atom increases monotonically with size. By analysing the energy level distribution, the Fermi level, HOMO-LUMO gaps, the electron affinities and the ionization potentials are calculated and the results are in reasonable agreement with experiment. These electronic properties are found to be strongly structure dependent, which can be used to determine which of the low-lying structures is observed experimentally. 相似文献
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4.
A systematic study on the structure and electronic properties of gold clusters doped each with one copper atom has been performed using the density functional theory. The average bond lengths in the Aun-1Cu (n ≤ 9) bimetallic clusters are shorter than those in the corresponding pure gold clusters. The ionization potentials of the bimetallic clusters Aun-1Cu (n 〈 9) are larger than those of the corresponding homoatomic gold clusters except for Aus. The energy gaps of the Au-Cu binary clusters are narrower than those of the Aun clusters except AuCu and Au3Cu. No obvious even-odd effect exists in the variations of the electron affinities and ionization potentials for the Aun-1Cu (n ≤ 9) clusters, which is in contrast to the case of gold clusters Aun. 相似文献
5.
Equilibrium geometries and electronic properties of BenLi (n=2-15) clusters from first principles
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This paper studies the equilibrium geometries and electronic properties of Ben and BenLi clusters, up to n=15, by using density-functional theory(DFT) at B3LYP/6-31G(d) level. The lowest-energy structures of Ben and BenLi clusters were determined. The results indicate that a single lithium impurity enhances the stability and chemical reactivity of the beryllium clusters. It finds that the geometries of the host clusters change significantly after the addition of the lithium atom for n ≥8. The lithium impurity prefers to be on the periphery of beryllium clusters, and occupies vertex sites. Both Be4Li, Be9Li, and Be13Li were found to be particularly stable with higher average binding energy, local peaks of second-order energy difference and fragmentation energies. For all the BenLi clusters studied, we found charge transfers from the Li to Be site and co-existence of covalent and metallic bonding characteristics. 相似文献
6.
硅锗团簇结构与电子性质的研究对于研发新型微电子材料具有重要意义. 将遗传算法和基于密度泛函理论的紧束缚方法相结合, 研究了SimGen(m+n=9)团簇的原子堆积结构和电子性质. 计算结果发现, SimGen(m+n=9) 团簇存在两种低能原子堆积稳定构型: 带小金字塔的五边形双锥堆积和带桥位Ge原子的四面体紧密堆积. 随着团簇内锗原子数目的逐渐增加, 两种堆积结构均出现明显的转变, 其中最低能量的几何结构由单侧带相邻双金字塔的五边形双锥结构转变为双侧带相邻单金字塔的五边形双锥结构. 随着原子堆积结构的变化, 团簇内原子电荷分布及电子最高占据轨道与电子最低未占据轨道的能隙随团簇内所含硅和锗元素组分的不同呈现出明显的差异. 相似文献
7.
采用相对论有效原子实势(RECP)近似和密度泛函(B3LYP)方法,选择LANL2DZ基组,优化得到了AunY(n=1—9)二元掺杂团簇稳定的基态结构和电子性质.研究结果表明,掺杂Y原子的AunY(n=1—9)团簇随n的变化,其电离势、电子亲合能和费米能级与Aun(n=2—9)一样具有“奇-偶”振荡效应;团簇离子的稳定性具有“幻数”现象,Au2Y+和Au6Y+比其他团簇离子更稳定,与质谱实验结果一致;同一团簇中,团簇最稳定的异构体(基态)是趋于Y原子有最大的邻近的Au原子数.
关键词:
Au-Y团簇
密度泛函
平衡几何结构
电子性质 相似文献
8.
A systematic study on the geometrical structures, electronic and magnetic properties of Au5H
n
(n=1–10) clusters has been performed by using the all-electron scalar relativistic density functional theory with generalized
gradient approximation at the PW91 level. It is found that all Au5H
n
clusters prefer to keep the planar structures like pure Au5 cluster, the Au5 structures in Au5H4, Au5H5 and Au5H6 clusters are distorted obviously. The adsorption of a number of hydrogen atoms enhances the stability of Au5 cluster and all Au5H
n
clusters are more stable than pure Au5 cluster energetically. The odd-even alteration of magnetic moment is observed in Au5H
n
clusters and may be served as the material with tunable code capacity of “0” and “1” by adsorbing odd or even number of H
atoms. It seems that the most favorable adsorption between Au5 cluster and a number of hydrogen atoms takes place in the case that the odd number of hydrogen atoms is adsorbed onto Au5 cluster and becomes Au5H
n
cluster with even number of valence electrons. 相似文献
9.
Effects of N-doping concentration on the electronic structure and optical properties of N-doped β-Ga2O3
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The electronic structures and the optical properties of N-doped β-Ga2O3 with different N-doping concentrations are studied using the first-principles method.We find that the N substituting O(1) atom is the most stable structure for the smallest formation energy.After N-doping,the charge density distribution significantly changes,and the acceptor impurity level is introduced above the valence band and intersects with the Fermi level.The impurity absorption edges appear to shift toward longer wavelengths with an increase in N-doping concentration.The complex refractive index shows metallic characteristics in the N-doped β-Ga2O3. 相似文献
10.
Ab initio investigation of the structural and unusual electronic properties of α-CuSe (klockmannite)
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In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe (klockmannite) using density functional theory. The studies in this work show that the best structural results, in comparison to the experimental values, belong to the PBEsol-GGA and WC-GGA functionals. However, the best results for the bulk modulus and density of states (DOSs) are related to the local density approximation (LDA) functional. Through utilized approaches, the LDA is chosen to investigate the electronic structure. The results of the electronic properties and geometric optimization of α-CuSe respectively show that this compound is conductive and non-magnetic. The curvatures of the energy bands crossing the Fermi level explicitly reveal that major charge carriers in CuSe are holes, whose density is estimated to be 0.86×1022 hole/cm3. In particular, the Fermi surfaces in the first Brillouin zone demonstrate interplane conductivity between (001) planes. Moreover, the charge carriers among them are electrons and holes simultaneously. The conductivity in CuSe is mainly due to the hybridization between the d orbitals of Cu atoms and the p orbitals of Se atoms. The former orbitals have the dual nature of localization and itinerancy. 相似文献
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通过采用密度泛函理论对Sc2,Y2和La2基本性质的计算,选择在较优理论水平下系统地研究了Scn, Yn和Lan(n=2—10)团簇的几何结构、稳定性、电子性质和磁性及其随团簇尺寸的变化趋势.此同族三种团簇的稳定性由原子密堆集几何结构效应决定,幻数均表现出一致的结果.Lan团簇的能隙比
关键词:
n')" href="#">Scn
n和Lan团簇')" href="#">Yn和Lan团簇
密度泛函理论
电子性质
磁矩 相似文献
14.
采用密度泛函理论对H2与Rhn(n=1—8)团簇的相互作用进行了系统研究.结果表明, RhnH2体系的最低能量结构是在Rhn团簇最低能量结构的基础上吸附H原子生长而成.吸附H原子没有改变Rhn团簇的结构, 键长是影响Rhn和RhnH2磁矩的主要因素.从优化后的几何结构可以看出吸附后的H2发生断键,表明H2分子发生了解离性吸附.当n≤5,H原子的吸附以桥位为主,当n≥6时,H原子开始出现空位吸附.H原子的吸附提高了Rhn的稳定性和化学活性,较小的吸附能表明H原子易从RhnH2中解离出来.二阶能量差分表明4是RhnH2和Rhn团簇的幻数.
关键词:
nH2和Rhn团簇')" href="#">RhnH2和Rhn团簇
平衡结构
电子性质 相似文献
15.
ZHANG Cai-rong ZHANG Bi-xia CHEN Yu-hong LI Wei-xue XU Guang-ji 《原子与分子物理学报》2006,23(B04):171-174
The hybrid density functional theory B3LYP with basis sets 6-31G* has been used to study on the equilibrium geometries and electronic structures of possible isomers of Si3N4 clusters. 24 possible isomers are obtained. The most stable isomer of Si3N4 is a 3D structure with 7 Si-N bonds and 2 N-N bonds that could beformed by 3 quadrangles. The bond properties of the most stable isomer was analyzed by using natural bond orbital method (NBO), the results suggest that the charges on Si and N atoms in Si-N bonds are quite large, so theinteraction of N-Si atoms in Si3N4 cluster is of strongly electric interaction. The primary IR and Raman vibrational frequency located at 1033.40 cm^-1, 473.63 cm^-1 respectively. The polarizabilities and hyperpolarizabilities of the most stable isomer are also analyzed. 相似文献
16.
A density functional theory structures,stabilities, and study on size-dependent electronic properties of bimetallic MnAgm (M=Na,Li; n + m ≤ 7) clusters
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The equilibrium geometries, relative stabilities, and electronic properties of MnAgm(M=Na, Li; n + m ≤ 7) as well as pure Agn, Nan, Lin (n ≤ 7) clusters are systematically investigated by means of the density functional theory. The optimized geometries reveal that for 2 ≤ n ≤ 7, there are significant similarities in geometry among pure Agn, Nan, and Lin clusters, and the transitions from planar to three-dimensional configurations occur at n = 7, 7, and 6, respectively. In contrast, the first three-dimensional (3D) structures are observed at n + m = 5 for both NanAgm and LinAgm clusters. When n + m ≥5, a striking feature is that the trigonal bipyramid becomes the main subunit of LinAgm. Furthermore, dramatic odd-even alternative behaviours are obtained in the fragmentation energies, secondorder difference energies, highest occupied and lowest unoccupied molecular orbital energy gaps, and chemical hardness for both pure and doped clusters. The analytic results exhibit that clusters with an even electronic configuration (2, 4, 6) possess the weakest chemical reactivity and more enhanced stability. 相似文献
17.
The structure, electronic and magnetic properties of HoSin(n= 1 - 12, 20) clusters have been widely investigated by first-principles calculation method based on density flmctional theory (DFT). From our calculation results, we find that for HoSin(n=1- 12) clusters except n = 7.10, the most stable structures are a replacement of Si atom in the corresponding pure Sin+1 clusters by Ho atom. The doping of Ho atom makes the stability of Si clusters enhance remarkably, and HoSin(n = 2, 5, 8, 11) clusters are more stable than their neighboring clusters. The magnetic moment of Ho atom in HoSin (n = 1 - 12, 20) clusters mainly comes from of electron of tto, and never quenches. 相似文献
18.
WANG Xin-qiang CHEN Yong 《原子与分子物理学报》2004,21(Z1):211-212
The structural and electronic properties of (CdSe)n(1≤n≤5) clusters are calculated using density functional theory within the pseudopotential and generalized gradient approximations. The calculated binding energies and highest occupied molecular orbital lowest unoccupied molecular orbital gaps are compared with those obtained within local density approximation. 相似文献
19.
A density functional theory study on size-dependent structures, stabilities, and electronic properties of the bimetallic MnAgm (M=Na, Li; n+m ≤ 7) clusters
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The equilibrium geometries, relative stabilities, and electronic properties of MnAgm (M=Na, Li; n+m≤ 7) as well as pure Agn, Nan, Lin (n≤ 7) clusters are systematically investigated by means of density functional theory. The optimized geometries reveal that for 2≤ n ≤ 7, there are significant similarities in geometry among pure Agn, Nan, and Lin clusters, and the transitions from planar to three-dimensional configurations occur at n=7, 7, and 6, respectively. In contrast, the first three-dimensional (3D) structures are observed at n+m=5 for both NanAgm and LinAgm cluters. When n+m ≥ 5, a striking feature is that the trigonal bipyramid becomes the main subunit of LinAgm. Furthermore, dramatic odd-even alternative behaviours are obtained in the fragmentation energies, second-order difference energies, highest occupied and lowest unoccupied molecular orbital energy gaps, and chemical hardness for both pure and doped clusters. The analytic results exhibit that clusters with even electronic configuration (2, 4, 6) possess weakest chemical reactivity and more enhanced stability. 相似文献
20.
Ab initio calculations of accurate dissociation energy and analytic potential energy function for the second excited state B1∏ of 7LiH
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The reasonable dissociation limit of the second excited singlet state
B1∏ of 7LiH molecule is obtained. The accurate dissociation energy and
equilibrium geometry of the B1\Pi state are calculated using a
symmetry-adapted-cluster configuration--interaction method in full active space. The
whole potential energy curve for the B1∏ state is obtained over the
internuclear distance ranging from about 0.10nm to 0.54nm, and has a least-square
fit to the analytic Murrell--Sorbie function form. The vertical excitation energy is
calculated from the ground state to the
B1∏ state and compared with previous theoretical results. The
equilibrium internuclear distance obtained by geometry optimization is found to be
quite different from that obtained by single-point energy scanning under the same
calculation condition. Based on the analytic potential energy function, the harmonic
frequency value of the B1∏ state is estimated. A comparison of the
theoretical calculations of dissociation energies, equilibrium interatomic distances
and the analytic potential energy function with those obtained by previous
theoretical results clearly shows that the present work is more comprehensive and in
better agreement with experiments than previous theories, thus it is an improvement
on previous theories. 相似文献