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1.
Equilibrium geometries, relative stabilities, and magnetic properties of small AunMn (n=1-8) clusters have been investigated using density functional theory at the PW91P86 level. It is found that Mn atoms in the ground state AunMn isomers tend to occupy the most highly coordinated position and the lowest energy structure of AunMn clusters with even n is similar to that of pure Aun+1 clusters, except for n=2. The substitution of Au atom in Aun+1 cluster by a Mn atom improves the stability of the host clusters. Maximum peaks are observed for AunMn clusters at n=2, 4 on the size dependence of second-order energy differences and fragmentation energies, implying that the two clusters possess relatively higher stability. The HOMO-LUMO energy gaps of the ground state AunMn clusters show a pronounced odd-even oscillation with the number of Au atoms, and the energy gap of Au2Mn cluster is the biggest among all the clusters. The magnetism calculations indicate that the total magnetic moment of AunMn cluster, which has a very large magnetic moment in comparison to the pure Aun+1 cluster, is mainly localized on Mn atom. 相似文献
2.
The equilibrium geometries and electronic properties of AunAl,
up to n=13, have been systematically investigated using the density
functional theory. The results show that, for the AunAl
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, AunAl 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. 相似文献
3.
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
4.
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 –1Rb 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. 相似文献
5.
M. X. Chen X. H. Yan S. Wei 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):513-517
Base on the density-functional theory, the structural and magnetic
properties of AunTi2
+ (
) clusters are investigated. The
two titanium atoms form a dimer in the gold clusters. The second-order
energy differences and HOMO-LUMO gap provide a clear explanation of the
abundance peaks and odd-even staggering observed recently in
photofragmentation experiments. The magnetism of AunTi2
+
cluster shows an odd-even effect when n increases from 1 to 4 and drops to
zero at n=5 and 7. The local magnetic moment and charge partition of Ti 4s,
3d orbitals are discussed. The peculiar magnetic properties are related to the
structures and the hybridization between the Au 5d, 6s states and Ti 3d, 4s
states. 相似文献
6.
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 ?1Ca 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. 相似文献
7.
An all-electron scalar relativistic calculation on AunH2S (n = 1-13) clusters has been performed by using density functional theory with the generalized gradient approximation at PW91 level. The small gold cluster would like to bond with sulfur in the same plane and the H2S molecule prefers to occupy the on-top and single fold coordination site in the cluster. The Aun structures and H2S molecule in all AunH2S clusters are only slightly perturbed and still maintain their structural integrity. After adsorption, the S-H, H-H bond-lengths and most Au-Au bond-lengths are elongated, only a few Au-Au bond-lengths far from H2S molecule are shortened. The reactivity enhancement of H2S molecule is obvious and the strong gold-sulfur bond is observed expectedly. The most favorable adsorption takes place in the case that the H2S molecule is adsorbed by an even-numbered Aun cluster and becomes AunH2S cluster with even number of valence electrons. It is believed that the strong scalar relativistic effect is favorable to H2S molecule adsorption onto small gold clusters and is also one of the important reasons for the strong gold-sulfur bond. 相似文献
8.
The geometrical, electronic, and magnetic properties of small Au n V (n?=?1–8) clusters have been investigated using density functional theory at the PW91 level. An extensive structural search indicates that the V atom in low-energy Au n V isomers tends to occupy the most highly coordinated position and the ground-state configuration of Au n V clusters favors a planar structure. The substitution of a V atom for an Au atom in the Au n +1 cluster transforms the structure of the host cluster. Maximum peaks are observed for the ground-state Au n V clusters at n?=?2 and 4 for the size dependence of the second-order energy differences, implying that the Au2V and Au4V clusters possess relatively higher stability. The energy gap of the Au3V cluster is the largest of all the clusters. This may be ascribed to its highly symmetrical geometry and closed eight-electron shell. For ground-state clusters with the same spin multiplicity, as the clusters size increases, the vertical ionization potential decreases and the electron affinity increases. Magnetism calculations for the most stable Au n V clusters demonstrate that the V atom enhances the magnetic moment of the host clusters and carries most of the total magnetic moment. 相似文献
9.
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
10.
Geometries, stabilities, and electronic properties of Be-doped gold clusters: a density functional theory study
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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. 相似文献
11.
The possible stable geometrical configurations and the relative stabilities of the lowest-lying isomers of copper-doped gold clusters,Au n Cu (n=1-7),are investigated using the density functional theory.Several low-lying isomers are determined.The results indicate that the ground-state Au n Cu clusters have planar structures for n=1-7.The stability trend of the Au n Cu clusters (n=1-7),shows that odd-numbered Au n Cu clusters are more stable than the neighbouring even-numbered ones,thereby indicating the Au 5 Cu clusters are magic cluster with high chemical stability. 相似文献
12.
Y. Li Y. P. Cao Y. F. Li S. P. Shi X. Y. Kuang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):7
The ab initio method based on density functional theory at the PW91PW91 level has been employed to systematically study the
structures, stabilities, electronic, and magnetic properties of gold clusters with or without silicon/phosphorus doping. The
optimized geometries show that the most stable isomers for Au
n
Si2 and Au
n
P2 (n = 1–8) clusters prefer a three-dimensional structure when n = 2 and n = 3 upwards, respectively, and they can be viewed as grown from the already observed Au
n−1M2 (M = Si, P). The relative stabilities of calculated Au
n
M2 (M = Si, P) clusters have been analyzed through the atomic average binding energy, fragmentation energy, second-order difference
of energy, and HOMO-LUMO gap. A pronounced odd-even alternative phenomenon indicates that the clusters with even-numbered
valence electrons possess a higher stability than their neighboring ones. For both systems, natural population analysis reveals
that electronic properties of dopant atoms in the corresponding configuration are mainly related to s and p states. We also investigated magnetic effects of clusters as a function of cluster size, however, their oscillatory magnetic
moments were found to vary inversely to the fragmentation energy, second-order difference of energy, and HOMO-LUMO gap. 相似文献
13.
Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [AunRb]+ and Aun + 1+ (n = 1–10) clusters. For the lowest energy structures of [AunRb]+ 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 [AunRb]+ clusters in the region of n = 1–10. The charges in [AunRb]+ clusters transfer from the Rb atoms to Aun 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 [AunRb]+ clusters is Rb+ cation ejection. The electronic localisation function (ELF) analysis of the [AunRb]+ clusters shown that strong interactions are not revealed in this study. 相似文献
14.
M. Vogel K. Hansen A. Herlert L. Schweikhard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):73-76
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 相似文献
15.
16.
X. J. Kuang X. Q. Wang G. B. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(1):111-122
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. 相似文献
17.
X. J. Kuang X. Q. Wang G. B. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(1):71-80
An all-electron scalar relativistic calculation on
Au
n
NO (n = 1–10) clusters has been performed by using density functional
theory with the generalized gradient approximation at the PW91 level. The
small gold cluster would like to bond with nitric and the nitric monoxide
molecule prefers to occupy the on-top and single fold coordination site. The
Au
n
structures in all Au
n
NO clusters are only distorted slightly
and still keep the planar structures. With the bend of Au-N-O bond, the
structures of Au
n
NO clusters evolve from the 2D structure to 3D
structure. The most favorable adsorption between small gold cluster and
nitric monoxide molecule takes place in the case that nitric monoxide
molecule is adsorbed onto an odd-numbered pure Au
n
cluster and becomes
odd-numbered Au
n
NO cluster with even number of valence electrons. The
scalar relativistic effect strengthens the Au–Au, Au–N interaction and
weakens the N–O interaction, appearing as the shorter Au–Au, Au–N
bond-length and the longer N–O bond-length. The differences between our work
and previous work are believed to be the reflection of the scalar
relativistic effect. 相似文献
18.
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. 相似文献
19.
R. Mitri C. Bürgel J. Burda V. Bonai-Koutecký P. Fantucci 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):41-44
Bimetallic silver-gold clusters are well suited to study
changes in metallic versus
ionic properties involving charge transfer as a function of
the size and the composition. We present structures, ionization
potentials (IP) and vertical detachment energies (VDE) for
neutral and charged bimetallic
AunAgm (
2(n +
m)5) clusters obtained from
density functional level of theory. In the stable structures of
these clusters Au atoms assume positions which favor charge
transfer from Ag atoms. In clusters with equal numbers of hetero
atoms (n =
m = 1- 4) heteronuclear
bonding is preferred to homonuclear bonding, giving rise to
large values of ionization potentials. For larger clusters
(n=m=5, 10) stable structures do not favor
neither hetero bonding nor segregation into the single
components, although they exhibit more metallic than ionic
features. This remains valid also for
Au8Ag12 cluster
characterized by strong charge transfer to gold subunit. The
influence of doping of pure gold clusters with silver atoms on
VDE and IP values is discussed in context of their reactivity
towards O2 and CO molecules. As a
starting point we consider reactivity towards CO and
O2 molecules on the example of
AgAu- dimer. The results show that
the catalytic cycle can be fullfilled. 相似文献
20.
Geometrical, electronic, and magnetic properties of the Sc-doped gold clusters, AunSc (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 AunSc isomers tends to occupy the most highly coordinated position. The substitution of a Sc atom for an Au atom in the Aun+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 D2h symmetry. The relative stabilities and electronic properties of the lowest-energy AunSc 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 AunSc (n=2-8) clusters gradually decreases for even n and is completely quenched for odd n. 相似文献