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1.
J. Moc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):247-252
Five doublet isomers of the Al3H2 cluster lying
within a narrow range of 5 kcal/mol, along with the isomerization transition
states connecting them, have been located with the coupled-cluster CCSD(T)
and DFT methods. The two most stable doublet structures, the C2v planar
including the two Hs bound terminally and C1 non-planar showing one H
in terminal site and the other in threefold site are found to be essentially
degenerate. Although the reaction of Al3 with H2 to yield
Al3H2 is found to be significantly exothermic, by 23.5 kcal/mol,
this hydrogenation is impeded by a considerable kinetic barrier of 16 kcal/mol. Our result is consistent with the observed
lack of reactivity of
Aln towards H2(D2) for n=3 under thermal conditions [3].
The quartet Al3H2 isomers are predicted to lie 16–21 kcal/mol higher
in energy than the doublet analogues. Further dimerization of
Al3H2 to form Al6H4 has also been examined.
Electronic supplementary material Supplementary Online Material 相似文献
2.
S. O. Adamson 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(1):143-152
The stationary points of the potential energy surfaces for the reactions C2H2 + OH and C2 + H2O are calculated using density functional theory and the coupled cluster method. The relative energies and geometric parameters of the stable intermediates and transition states are in good agreement with the results of independent studies. In most cases, the relative energies differ from the earlier published values by no more than 3 kcal/mol, whereas the rotational constants, by 1–2%. The mechanism of the reaction CCOH2 → C2 + H2O is studied in detail. The possible sources of errors in the calculation methods are examined. 相似文献
3.
L. Guo H.-S. Wu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):259-267
Geometries, electronic states and electron affinities of AlmAsn and AlmAs n (m+n=2–5) clusters have been examined using
four hybrid and pure density functional theory (DFT) methods. Structural
optimization and frequency analyses are performed using a 6-311+G(2df)
one-particle basis set. The geometries are fully optimized with each DFT
method independently. The three types of energy separations reported in this
work are the adiabatic electron affinity (EAad), the vertical electron
affinity (EAvert), and the vertical detachment energy (VDE). The
calculation results show that the singlet structures have higher symmetry
than that of doublet structures. The best functional for predicting
molecular structures was found to be BLYP, while other functionals generally
underestimated bond lengths. The largest adiabatic electron affinity,
vertical electron affinity and vertical detachment energy, obtained at the
6-311+G(2df)/BP86 level of theory, are 2.20, 2.04 and 2.27 eV (AlAs), 2.13,
1.94 and 2.38 eV (AlAs2), 2.44, 2.39 and 2.47 eV (Al2As), 2.09,
1.80 and 2.53 eV (Al2As2), 2.01, 1.57 and 2.36 eV (AlAs3),
2.32, 2.11 and 2.55 eV (Al2As3), 2.40, 1.45 and 3.26 eV
(AlAs4), 1.94, 1.90 and 2.07 eV (Al4As), respectively. However, the
BHLYP method gives the largest values for EAad and EAvert of
Al3As and EAad of Al3As2, respectively. For the
vibrational frequencies of the AlnAsm series, the B3LYP method
produces good predictions with the average error only about 10 cm-1 from available experimental and theoretical values. The other three functionals overestimate or underestimate the vibrational
frequencies, with the worst predictions given by the BHLYP method. 相似文献
4.
5.
H. Nagao K. Awazu S. Hayakawa K. Iwamoto M. Toyoda T. Ichihara 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):279-287
Various dissociation channels of silver bromide cluster ion
Ag2Br+ and silver cluster ion Ag3
+ were observed in
high-energy collisionally-activated dissociation (CAD) using a Cs target.
The fragment patterns of the high-energy CAD were compared with those of the
metastable dissociation and low-energy CAD. The difference in the fragment
patterns between the high-energy CAD and the other dissociation methods was
explained in terms of the internal energy distributions. The dissociation
mechanisms of neutral silver bromide cluster Ag2Br and silver cluster
Ag3 were also investigated by charge inversion mass spectrometry using
the Cs target. While the fragment ions AgBr- and Ag2
- were
dominantly observed in the charge inversion spectrum of Ag2Br+,
the undissociated ion Ag3
- was observed as a predominant peak in
the case of Ag3
+. The dissociation behavior of Ag2Br*
can be explained on the basis of the calculated thermochemical data.
Contrary to this, the predominant existence of the undissociated
Ag3
- cannot be explained by the reported thermochemical data. The
existence of undissociated Ag3
- suggests that the dissociation
barrier is higher than the internal energy of Ag3
*
(theoretical: 1.03 eV, experimental: 2.31 eV) estimated from the ionization
potentials of Ag3 and Cs. 相似文献
6.
β-Ga2O3 nanowires have been synthesized using Ga metal and H2O vapor at 800 °C in the presence of Ni catalyst on the substrate. Remarkable reduction of the diameter and increase of the
length of the Ga2O3 nanowires are achieved by separation of Ga metal and H2O vapor before they reach the substrate. Transmission electron microscopy analyses indicate that the β-Ga2O3 nanowires possess a single-crystalline structure. Photoluminescence measurements show two broad emission bands centered at
290 nm and 390 nm at room temperature.
Received: 27 June 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +886-6/234-4496, E-mail: wujj@mail.ncku.edu.tw 相似文献
7.
F.v. Gynz-Rekowski W. Quester R. Dietsche D. C. Lim N. Bertram T. Fischer G. Ganteför M. Schach P. Nielaba Y. D. Kim 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):409-413
The possibility of using magic Si7 clusters to form a cluster material was studied experimentally and theoretically. In experiments Si7 clusters were deposited on carbon surfaces, and the electronic structure and chemical properties of the deposited clusters
were measured using X-ray photoelectron spectroscopy (XPS). A non bulk-like electronic structure of Si7 was found in the Si 2p core level spectra. Si7 is suggested to form a more stable structure than the non-magic Si8 cluster and Si atoms upon deposition on carbon surfaces. Theoretically it was possible to study the interaction between the
clusters without the effect of a surface. Density functional theory (DFT) calculations of potential curves of two free Si7 clusters approaching each other in various orientations hint at the formation of cluster materials rather than the fusion
of clusters forming bulk-like structures. 相似文献
8.
The isomers of the carbonyl sulfide (OCS) molecule are investigated in detail at CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level of theory. One cyclic isomer was identified along with three different linear minima of the OCS molecule. Three interconversion transition states were also located between cyclic and linear forms of OCS. Among these four isomers, the singlet potential energy surface (PES) for the molecule–molecule reaction between the three most energetically favoured isomers of OCS and H2O has been explored theoretically at the CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level. This singlet PES comprises of three paths. Path 1 is the reaction of linear OCS molecule with water producing the major product P1 (CO2?+?H2S), minor product P2 (S?+?HCOOH) and two isomers via 14 minima and 15 transition states. The Path 2 is an isomerization process in which cyclic isomer of OCS reacts with water molecule via another initial barrierless aduct producing five isomers of the OCS–H2O system through five interconversion transition states. The reaction of linear COS isomer with water is shown in Path 3. This path produces the radicals SH and COOH from another COS–H2O complex via a transition state. Among these three products, the product P1 is energetically most favoured. The overall exothermicity of the product channels for the formation of major product P1 on PES is calculated to be about 10.60?kcal/mol possessing initial high entrance barriers of 45.48 and 55.47?kcal/mol in two possible pathways. As the process is favoured thermodynamically but not kinetically, the reaction is expected to be very slow. 相似文献
9.
X. Liang Y.-H. Luo X.-J. Feng T. T. Cao L. X. Zhao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):93-101
The structures, binding energies, and electronic properties of
Cn and NaCn (n=2–12) clusters have been systematically
investigated using density functional theory (DFT). A number of
previously undiscovered isomers of NaCn clusters are reported,
including fan-like, linear and three-dimensional structures.
Moreover, NaCn clusters with even n are found to be more
stable than those with odd n, in contrast with
the case of Cn clusters. 相似文献
10.
M. S. B. Darby T. C. May-Smith R. W. Eason 《Applied Physics A: Materials Science & Processing》2008,93(2):477-481
We have demonstrated pulsed laser deposition of Nd-doped gadolinium gallium garnet on Y3Al5O12 by the simultaneous ablation of two separate targets of Nd:Gd3Ga5O12 (GGG) and Ga2O3. Such an approach is of interest as a method of achieving stoichiometry control over films whilst the growth parameters are
kept constant and optimal for high quality crystal growth. We show here how the stoichiometry and resultant lattice parameter
of a film can be controlled by changing the relative deposition rates from the two targets. Films have been grown with enough
extra Ga to compensate for the deficiency that commonly occurs when depositing only from a GGG target. We have also grown
crystalline GGG films with an enriched Ga concentration, and this unconventional approach to film stoichiometry control may
have potential applications in the fabrication of films with advanced compositionally graded structures. 相似文献
11.
Despite the fact that B3O is the second simplest B n O radical after BO, a controversy recently emerged concerning the molecular structure of its global minimum. Two recent theoretical groups predicted the linear quartet BBBO to be the ground isomer. By contrast, another recent theoretical group reported that B3O has a doublet B3-ring ground structure. Moreover, larger B n O clusters usually have low-lying B3-ring isomers. In order to determine the accurate energetic competition between linear and cyclic structures in both the doublet and quartet, and to understand the detailed isomerism between various isomers, which is vital for understanding the formation mechanism of B3O, we report the first potential energy surface (PES) study of B3O at various computational levels, including CCSD(T)/6-311+G(2df), CCSD(T)/aug-cc-pVTZ, CCSD(T)/aug-cc-pVQZ and G3B3 for the single-point energy, as well as B3LYP/6-311+G(d) and QCISD/6-311+G(d) for geometrical optimisation. It is shown that the isomers in the quartet state are all thermodynamically more stable than the corresponding doublet ones, and on both the quartet and doublet PESs, the linear form has the lowest energy. Therefore, our study on both linear and cyclic isomers shows that the linear quartet BBBO 4 01 is definitively the ground isomer. Although being much less stable than the quartet linear BBBO global minimum by >20 kcal mol?1, five cyclic isomers exist as local minima, with the bi-cyclic structure 4 02 possessing the smallest barrier of around 15 kcal mol?1. The dissociation energies for direct combination processes B3 + O, B2 + BO and B + B2O are discussed. The present work may be helpful in obtaining a deep understanding of the doping and oxidation process of pure B n clusters. 相似文献
12.
A. C. Reber S. N. Khanna J. S. Hunjan M. R. Beltran 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):221-224
Theoretical electronic structure studies on (ZnO)n (n= 2–18, 21) have
been carried out to show that the transition from an elementary ZnO molecule
to the bulk wurtzite ZnO proceeds via hollow rings, towers, and cages. Our
first principles electronic structure calculations carried out within a
gradient corrected density functional framework show that small
ZnnOn (n=2–7) clusters form single, highly stable rings.
Zn3O3 and the symmetric cage Zn12O12 are shown to be
particularly stable clusters. Among larger clusters, the most stable are
oblong cages, Zn15O15, Zn18O18, and Zn21O21,
which are reminiscent of nanotubes. 相似文献
13.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献
14.
V. Boutou A.R. Allouche F. Spiegelmann J. Chevaleyre M. Aubert Frécon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):63-73
The geometrical structure of ground state Ban clusters (n
=2-14) has been predicted from various types of calculations including two ab initio approaches used for the smaller sizes namely HF+MP2(
n
=2-6), DFT (LSDA)(
n
=2-6, 9) and one model approach HF+pairwise dispersion used for all sizes investigated here. The lowest energy configurations
as well as some isomers have been investigated. The sizes n
=4, 7 and 13 are predicted to be the relatively more stable ones and they correspond to the three compact structures: the tetrahedron,
the pentagonal bipyramid and the icosahedron. The growth behavior from Ba7 to Ba13 appears to be characterized by the addition of atoms around a pentagonal bipyramid leading to the icosahedral structure of
Ba13 which is consistent with the observed size-distribution of barium clusters. Values for vertical ionization potentials calculated
for n
=2-5 at the CI level are seen to be in quite good agreement with recent measures.
Received: 14 May 1997 / Received in final form: 2 February 1998 / Accepted: 27 February 1998 相似文献
15.
S. W. Tang L. L. Sun J. D. Feng H. Sun R. S. Wang Y. F. Chang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):197-204
A systematic investigation of D3 C32 fullerene and its derivatives C32Xn (X = H and Cl) has been performed using B3LYP/6-31G(d) method based on the density functional theory. The geometry structures,
reaction energies, relative stabilities, and electronic properties have been studied. By investigating the possible C32Xn (X = H and Cl) molecules, C32H2 and C32Cl2 behave more thermodynamically accessible with respect to other derivatives. The frontier molecular orbitals and electronic
density of states calculations of C32X2 system indicate that H and Cl passivation have less contribution to the electronic structures, but significantly improve
the stability of D3 C32 fullerene. Finally, the 13C NMR chemical shifts of C32H2 and C32Cl2 have been simulated to provide helpful information for further experiment identification. 相似文献
16.
M. S. Aleksanyan V. M. Arakelyan V. M. Aroutiounian A. Z. Adamyan G. E. Shahnazaryan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2010,45(6):291-296
Nanosize films of In2O3:Ga2O3 (96:4 weight %) have been deposited on a glassceramic substrate by the method of rf magnetron sputtering. The surfaces of
fabricated films were studied with use of a scanning electron microscope; sizes of grains were determined and the thicknesses
of films were measured. In order to prepare a gas-sensitive structure, a thin catalytic palladium layer and ohmic comb contacts
were deposited on the In2O3:Ga2O3 film surface by the method of ion-plasma sputtering. The sensitivity of sensors based on the glassceramic/In2O3:Ga2O3 (96:4 weight %)/Pd structure to different concentrations of propane and butane gas mixture, as well as to methane was investigated
at temperatures of working substance from 250 to 300°C. 相似文献
17.
B. Morosin C. Henderson J. E. Schirber 《Applied Physics A: Materials Science & Processing》1994,59(2):179-180
The direct solid-state synthesis of C60H2 has been demonstrated by controlling the amount of hydrogen introduced into the reaction with C60. Palladium hydride has been used as the source of hydrogen. The main product 1,2-C60 is the isomer predicted to have the lowest energy of the possible 23 isomers; in addition, small amounts of the thermodynamically most stable isomer of C60H4, 1,2,3,4-C60H4, have also been obtained. 相似文献
18.
J.M. Mestdagh M. Berdah N. Auby C. Dedonder-Lardeux C. Jouvet S. Martrenchard-Barra D. Solgadi J.P. Visticot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):291-302
The photodissociation of a chlorine molecule in the environment of a xenon cluster has been studied experimentally using the
real time pump and probe technique through the formation of an XeCl reaction product. The photodissociating system is probed
in such a way that the movement of a single chlorine atom in the xenon environment is detected. Various XenCl2 cluster sizes have been investigated leading to the distinction between uncapped, half-capped and doubly capped structures
for these clusters. These structures have a profound influence on the photodissociation dynamics. Retrapping of one chlorine
atomic fragment and stabilization of the XeCl reaction product is only observed for the half and doubly capped clusters. The
experimental work is complemented by classical molecular dynamics calculations to get a full picture of the photodissociation.
Received: 17 February 1998 / Received in final form and Accepted: 28 July 1998 相似文献
19.
Highly reduced fullerenes containing nearly 5 wt.% of dihydrogen can be synthesized using readily available reagents. Hydrides prepared from C60 by dissolving metal reductions give complex mixtures of unstable isomers of C60H36. High temperature syntheses using transfer hydrogenation reagents such as dihydroanthracene provide mainly two stable isomers of C60H36 that have been characterized spectroscopically. Dihydrogen can be removed thermally from these materials at 500 °C. The experimentally determined activation energy for the thermal removal of dihydrogen from C60H2 is 61.4 kcal/mol. This value is in good agreement with the value determined computationally for a multi step radical reaction. The 92 kcal/mol barrier determined computationally for the concerted loss of dihydrogen reflects the symmetry-imposed barrier to dehydrogenation. PACS 81.05.Tp; 82.30.Cf; 82.56.Ub 相似文献
20.
N. Seeburrun H. H. Abdallah E. F. Archibong P. Ramasami 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(3):351-358
We hereby report a theoretical study on the equilibrium geometries, electronic structures and harmonic vibrational frequencies
of Ga2Se3, Ga3Se2 and their anions. The ground and low-lying excited states of Ga2Se3−, Ga2Se3, Ga3Se2− and Ga3Se2 are studied at the B3LYP and/or MP2 and CCSD(T) levels in conjunction with 6-311+G(d) and 6-311+G(2df) one particle basis
sets. Ga2Se2− adopts the C2v
kite geometry while Ga2Se3 has a ‘V’ geometry. Ga3Se2− has a three-dimensional ‘D3h
’ geometry and Ga3Se2 prefers the three-dimensional ‘C2v
’ structure. Electron detachment energies from the ground electronic states of the anions to several neutral states are reported
and discussed. At CCSD(T)//MP2 level, the adiabatic electron affinity (AEA) of Ga2Se3 is calculated to be 3.23 eV when using the 6-311+G(2df) basis set and that of Ga3Se2 is 2.77 eV with the 6-311+G(d) basis set. The findings of this research are analyzed and compared with gallium oxide and
sulfide analogues. 相似文献