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1.
Ambrish K. Srivastava 《Molecular physics》2014,112(12):1639-1644
We perform density functional calculations on the ground state geometries of MOn clusters (M = Ni, Pd, Pt; n = 1–5) in neutral as well as anionic forms. Our calculations reveal that Ni can bind up to three O atoms while Pd and Pt bind with four O atomically indicating the fact that the maximum oxidation state of Ni can take the value of +6 and can go as high as +8 in case of Pd or Pt. The electron affinities of MOn suggest that these species behave as superhalogens for n ≥ 2. The large electron affinities of MOn species along with stability of their anions further point towards the synthesis of new class of compounds having unusual oxidising capabilities. 相似文献
2.
利用密度泛函理论在B3LYP/6-311G*水平上对叠氮化合物(HMgN3)n(n=1–5)团簇各种可能构型进行了几何优化,预测了各团簇的最稳定结构. 并对最稳定结构的成键特性、电荷分布、振动特性及稳定性进行理论研究. 结果表明:HMgN3团簇最稳定结构为直线型;(HMgN3)n(n=2,5)团簇最稳定结构为叠氮基中N原子和金属原子相连构成Mg–N–Mg结构;(HMgN3)n(n=3,4)团簇最稳定结构为叠氮基与Mg原子相互链接形成的环状结构. 团簇最稳定结构中金属Mg原子均显示正电性,H原子均显示负电性,叠氮基中间的N原子显示正电性、两端的N原子显示负电性,且与Mg原子直接作用的N原子负电性更强. Mg–N键和Mg–H键为典型的离子键,叠氮基内N原子之间是共价键. 团簇最稳定结构的红外光谱分为三部分,其最强振动峰均位于2258–2347 cm-1,振动模式为叠氮基中N–N键的反对称伸缩振动. 叠氮基在团簇和晶体中结构不变,始终以直线型存在. 稳定性分析显示,(HMgN3)3团簇相对于其他团簇更为稳定.
关键词:
3)n(n=1–5)团簇')" href="#">(HMgN3)n(n=1–5)团簇
叠氮基
密度泛函理论
结构与性质 相似文献
3.
Mao Ai-Jie Kuang Xiao-Yu Chen Gang Zhao Ya-Ru Li Yan-Fang Lu Peng 《Molecular physics》2013,111(11):1485-1494
The ab initio method based on density functional theory at the B3PW91 level has been applied to study the geometric, electronic, and magnetic properties of neutral and anionic Au n Pd (n?=?1–9) clusters. The results show that the most stable geometric structures adopt a three-dimensional structure for neutral Au7Pd and Au8Pd clusters, but for anionic clusters, no three-dimensional lowest-energy structures were obtained. The relative stabilities of neutral and anionic Au n Pd clusters were analysed by means of the dependent relationships between the binding energies per atom, the dissociation energies, the second-order difference of energies, the HOMO–LUMO energy gaps and the cluster size n, and a local odd–even alternation phenomenon was found. Natural population analysis indicates the sequential transfer from the Pd atom to the Au n frame in Au1,2,3,5Pd and Au2,3Pd? clusters, and from the Au n frame to the Pd atom in other clusters. Much to our surprise, irrespective of whether it is the total magnetic moment or the local magnetic moment, the magnetic moment presents an odd–even alternation phenomenon as a function of the cluster size n. The magnetic effects are mainly localized on the various atoms (Au or Pd) for different cluster size n. 相似文献
4.
V. Kumar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):227-232
We report the recent findings of metal (M) encapsulated
clusters of silicon from computer experiments based on
ab initio total energy
calculations and a cage shrinkage and atom removal approach. Our
results show that using a guest atom, it is possible to wrap
silicon in fullerenelike (f)
structures, as sp2 bonding is not
favorable to produce empty cages unlike for carbon. Transition M
atoms have a strong bonding with the silicon cage that are
responsible for the compact structures. The size and structure
of the cage change from 14 to 20 Si atoms depending upon the
size and valence of the M atom. Fewer Si atoms lead to
relatively open structures. We find cubic,
f, Frank-Kasper (FK)
polyheral type, decahedral, icosahedral and hexagonal structures
for M@Sin with n = 12-16 and several different M
atoms. The magic behavior of 15 and 16 atom Si cages is in
agreement with experiments. The FK polyhedral cluster,
M@Si16 has an exceptionally large density
functional gap of about 2.35 eV calculated within the
generalized gradient approximation. It is likely to give rise to
visible luminescence in these clusters. The cluster-cluster
interaction is weak that makes such clusters attractive for
cluster assembled materials. Further studies to stabilize
Si20 cage with M = Zr, Ba, Sr, and Pb
show that in all cases there is a distortion of the
f cage. Similar studies on M
encapsulated germanium clusters show FK polyhedral and
decahedral isomers to be more favorable. Also perfect
icosahedral M@Ge12 and
M@Sn12 clusters have been obtained with
large gaps by doping with divalent M atoms. Recent results of
the H interaction with these clusters, hydrogenated silicon
fullerenes as well as assemblies of clusters such as nanowires
and nanotubes are briefly presented. 相似文献
5.
Liang Chen Cheng-gang Zhou Jin-ping Wu Han-song Cheng 《Frontiers of Physics in China》2009,4(3):356-366
In this review, we present our recent first principles studies on the sequential H2 dissociative chemisorption and H desorption on the Pt
n
and Pd
n
clusters (n=2–9, 13). Upon full saturation by H atoms, the calculated H2 dissociative chemisorption energy and H desorption energy on
Pt13 and Pd13 clusters are similar to the corresponding values on smaller close-packed clusters. Indeed, the catalytic performances of
these subnano clusters do not vary significantly with the particle sizes or shapes. Instead, they are dependent on the surface
metal atoms which can be accessed by H atoms. In addition to the coverage dependency of the H2 dissociative chemisorption and H sequential desorption energies, the phase transition of both Pt13 and Pd13 from the icosahedral to fcc-like structures at certain H coverage was also investigated.
相似文献
6.
7.
Ambrish K. Srivastava 《Molecular physics》2014,112(15):1963-1968
First principle density functional approach is employed to investigate the ground-state geometries and stabilities of ReOn species (n = 1–5) in neutral as well as anionic forms. It is revealed that Re can bind stably with five O atoms indicating the maximum oxidation state of Re as high as +10. The electron affinities of ReOn suggest that these species behave as superhalogens for n ≥ 3 which become as large as 7.25 eV for n = 5. The interaction of ReOn superhalogens with appropriate alkali metals is stronger than that of halogens leading to the synthesis of more stable complex compounds. This idea is illustrated by considering the interaction of ReOn superhalogens with K atom, forming KReOn complexes which are relatively more stable than KF molecule. In such complexes, ReOn unit closely mimics the behaviour of F atom when compared with KF. 相似文献
8.
The geometric structures, stabilities, and electronic properties of small size anionic [AunRb]? and Aun+1? (n = 1–10) clusters have been systematically investigated by using density functional theory. The optimised geometries show that the structures of [AunRb]? clusters favour the three-dimensional structure at n ≥ 8. The Rb atoms tend to occupy the most highly coordinated position and form the largest probable number of bonds with gold atoms. One Au atom capped on [Aun-1Rb]? structures is the dominant growth pattern for n = 2–8 and Rb atom capped on Aun? structures for n = 9–10. The averaged atomic bonding energies, fragmentation energies, second-order difference of energies, and highest occupied molecular orbital–lowest unoccupied molecular orbital gaps exhibit a pronounced even–odd alternations phenomenon. The charges in [AunRb]? clusters transfer from the Rb atoms to Aun host. In addition, it is found that the most favourable dissociation channel of the [AunRb]? clusters is to eject a Rb atom and the highest energy dissociation path is Rb? anion ejection. 相似文献
9.
Somesh Kr. Bhattacharya Anjali Kshirsagar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(3):609-619
We study Cd vacancy formation in prototype stoichiometric and non-stoichiometric
CdTe clusters with and without
passivation. For certain clusters like Cd13Te16,
vacancy leads to severe distortion of the geometry due to propagation
of defect. Annealing of the vacancy out of the cluster is observed in all unpassivated clusters.
Passivated clusters retain their initial geometry and
vacancy induced structural distortions are not seen in
these clusters since the defect gets localized. Vacancy also induces
intragap states. However, it was observed that
the passivation of the dangling bonds created by the vacancy removes the
intragap states. In an attempt to have CdTe clusters with extrinsic carriers,
we substituted a Cd atom by its adjacent atoms Pd/Ag/In/Sn in these CdTe clusters.
Substitutional doping of Cd by metal atoms increases the stability of unpassivated
clusters. For certain clusters, metal atom doping leads to a half-metallic character.
Pd/Ag-doped clusters are p-type semiconductors whereas In-doped clusters are n-type
semiconductors. Sn doping in these clusters does not result in n-type semiconductors. 相似文献
10.
利用光电子能谱及密度泛函理论计算对TiGen-(n=7~12)团簇的几何结构及电子特性等进行了系统研究. 对于TiGen-负离子及中性TiGen,在n=8时出现了钛原子半内嵌的船型结构;在n=9~11时,新增的锗原子加盖到这种船型结构上,逐步形成钛原子完全内嵌的结构. TiGe12- 团簇具有一种钛原子内嵌的变形六棱柱结构. 自然布居分析结果显示,对于n=8~12的TiGen-/0 团簇,随着内嵌结构的形成,有电子从锗原子转移到钛原子,说明其电荷转移方式与结构演变密切相关. 相似文献
11.
A systematic study of the X2Aun (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 Aun 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 La2Au1–9, Y2Au1–7, and Sc2Au1–4 clusters, the charges transfer from X atoms to the Aun frames. The total magnetic moments of X2Aun clusters exist distinctly odd–even alternation behaviours except for La2Au4 and Sc2Au4 clusters. 相似文献
12.
从第一性原理出发,利用密度泛函理论中的广义梯度近似对ZrnFe(n=2—13)团簇进行了结构优化、能量和频率计算.在充分考虑自旋多重度的前提下,对每一具体尺寸的团簇,得到了多个平衡构型,并根据能量高低确定了团簇的基态结构.综合团簇的结合能、二阶能量差分以及团簇的最高占据轨道和最低未占据轨道间的能隙可知Zr5Fe,Zr7Fe和Zr12Fe团簇的稳定性相对较高,Zr12Fe团簇的结构是具有Ih对称性的正二十面体,而且Zr12Fe的稳定性在所有团簇中是最高的.另外,不仅Zr5Fe,Zr7Fe和Zr12Fe团簇的稳定性相对较高,而且它们均为磁性团簇(而Zrn团簇的磁矩在n≥5时已经发生了淬灭),由此可知通过选择合适的掺杂元素可能得到高稳定的磁性团簇.从Mulliken布居分析结果可知,除了在Zr12Fe团簇中Fe原子失去少量电荷外,其他团簇中Fe原子均从Zr原子那里得到了一定量电荷,即Fe原子在ZrnFe(n=2—13,n≠12)团簇中是电子受体. 相似文献
13.
This study is interested in the illustration of ab initio potential energy curves for Ba+Arn (n = 1–4) clusters. The electronic structures of these molecules are calculated using [Ba2+] and [Ar] non-empirical core pseudo-potentials complemented by the core polarisation operators for both atoms, which allow the consideration of core valence correlation effects. The structure and stabilities of Ba+Arn (n = 1–4) clusters are investigated. These molecules are treated as one-electron active system. Spectroscopic constants and vibrational energy levels have been derived from their potentials. The analysis of the geometric forms, basing on the potential energy curves and the spectroscopic constants, clearly shows the importance of rare gas induced dipole. We also show that the dipolar interactions can influence the coupling between atoms. 相似文献
14.
利用密度泛函理论(DFT)的B3PW91方法,在6-311G水平上对BMgn,AlMgn(n=1—12)团簇进行了几何结构优化和电子性质分析. 发现随着原子个数的增加, B原子进入镁团簇的内部, 而AlMgn和镁团簇有相似的生长模式. B,Al原子的掺杂均能使镁团簇的平均结合能增大,稳定性增强, BMgn,AlMgn关键词:
密度泛函理论
最低能量结构
n和AlMgn团簇')" href="#">BMgn和AlMgn团簇
NBO电荷布居 相似文献
15.
J. Zhao Y. Luo G. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):309-316
Tight-binding model is developed to study the structural and electronic properties of silver clusters. The ground state structures
of Ag clusters up to 21 atoms are optimized by molecular dynamics-based genetic algorithm. The results on small Agn clusters (n = 3-9) are comparable to ab initio calculations. The size dependence of electronic properties such as density of states, s-d band separation, HOMO-LUMO gap, and ionization potentials are discussed. Magic number behavior at Ag2, Ag8, Ag14, Ag18, Ag20 is obtained, in agreement with the prediction of electronic ellipsoid shell model. We suggest that both the electronic and
geometrical effect play significant role in the coinage metal clusters.
Received 7 August 2000 相似文献
16.
K. Ohshimo H. Tsunoyama F. Misaizu K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):107-110
Intracluster electron transfer and oligomerization reaction were investigated by mass spectrometry of clusters of alkali metal
atom (M) with acrylonitrile (AN; CH2=CHCN). In the photoionization mass spectra of M(AN)n, magic numbers were clearly observed at n = 3k (k = 1-4 for M = Na and K, k = 1 for M = Li). The results of photodissociation of neutral K(AN)n indicate that the n = 3 cluster has an anomalous stability relative to other sizes of clusters. The C=C bond in vinyl molecules is also found
to be necessary to form the magic numbers by measuring the photoionization mass spectrum of K atom with propionitrile. These
results strongly support the intracluster anionic oligomerization reaction initiated by electron transfer from the alkali
atom. The quantum chemical calculations have revealed that the evaporation induced by excess energy generated by intracluster
oligomerization is important to form the magic numbers in the present clusters.
Received 29 November 2000 相似文献
17.
The lowest-energy structures and the electronic properties of Mo2nNn(n=1-5) clusters have been studied by using the density functional theory(DFT) simulating package DMol 3 in the generalized gradient approximation(GGA).The resulting equilibrium geometries show that the lowest-energy structures are dominated by central cores which correspond to the ground states of Mo n(n = 2,4,6,8,10) clusters and nitrogen atoms which surround these cores.The average binding energy,the adiabatic electron affinity(AEA),the vertical electron affinity(VEA),the adiabatic ionization potential(AIP) and the vertical ionization potential(VIP) of Mo2nNn(n=1-5) clusters have been estimated.The HOMO-LUMO gaps reveal that the clusters have strong chemical activities.An analysis of Mulliken charge distribution shows that charge-transfer moves from Mo atoms to N atoms and increases with cluster size. 相似文献
18.
采用密度泛函理论中的广义梯度近似(GGA) 对 Run Au和Run 团簇的几何构型进行优化,并对能量、频率、电子性质和磁性质进行了计算. 结果表明,Run Au团簇的最低能量结构可以通过Au原子代替Run+1团簇中的Ru原子生长而成.除了局域的结构畸变,Run Au和Run+1团簇具有相似的几何结构.二阶能量差分、电离势、亲和势和分裂能表明Ru5, Ru8, Ru5Au, Ru8Au 是稳定的团簇,Au的掺杂没有改变Run 的相对稳定性.通过电子性质的分析发现,当Au原子掺杂在Run 中,团簇的化学活性增加,且团簇的能隙主要由电子的配对效应决定;对于大多数团簇来说,Au原子掺杂提高了Run Au的磁矩.
关键词:
n Au和Run 团簇')" href="#">Run Au和Run 团簇
几何结构
电子性质 相似文献
19.
The stability and electronic properties of the Rh-doped ruthenium clusters and their reactivity towards NH3 molecule have been studied using DFT calculations with the BLYP-D3/SDD level of theory. The results show that the doping of Ru clusters with Rh atom improves the catalytic performances of pure Ru clusters, and the Ru5Rh and Ru7Rh clusters are assumed to be less reactive than their neighbours. The interaction of NH3 with clusters exhibits that the Ru atoms are preferred adsorption sites for the NH3 molecule, and the adsorption takes place between the Ru atom of clusters and the N atom of NH3 molecule. The adsorption energies of NH3 on RunRh clusters are in the range of ?101.5 to ?218.4?kJ?mol?1, suggesting a strong adsorption between both species. Upon adsorption process, the electronic properties of the RunRh clusters were substantially changed. The variation of Eg (ΔEg) for the RunRh (n?≥?7) clusters is very important (ΔEg?≥?55%), suggesting that these clusters are very sensitive to the NH3 molecule. Hence, these clusters can be employed as nanosensors for the detection of the NH3 gas. 相似文献