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1.
In the present study, the adsorption behaviour of methanol (CH3OH) and ethanol (C2H5OH) molecules over heterofullerene C59B surface is studied by density functional theory calculations. This heterofullerene is obtained from C60 by substituting a carbon atom with a boron atom and relaxing self-consistently the structure to the local minimum. The adsorption of CH3OH and C2H5OH on the C59B is exothermic and the relaxed geometries are stable. The CH3OH and C2H5OH adsorption can also induce a change in the highest occupied molecular orbital and the lowest unoccupied molecular orbital energy gap of the nanocage. The dehydrogenation pathways of CH3OH and C2H5OH via O–H and C–H bonds scission are also examined. The results indicate that O–H bond scission is the most favourable pathway on the C59B surface. 相似文献
2.
We employed density functional theory to characterise H2S adsorption, and dissociation on the pristine and Stone–Wales (SW) defected BC3 graphenes. H2S is predicted to be weakly adsorbed on the pristine graphene with the adsorption energy of about 7.11 kcal/mol. Two types of SW defects were generated by rotating a C–C bond (SW-CC) or a B–C bond (SW-BC) by about 90°. We predict that, in contrast to SW-BC, dehydrogenation of H2S is energetically more favourable on the SW-CC compared to the associative adsorption. It is also found that SW-CC formation is more favourable than the formation of SW-BC. Molecular adsorption of H2S on both of the SW defected sheets is more favourable than that on the pristine sheet. The preferable adsorption process on the SW-BC and SW-CC defected graphene sheets is via associative and dissociative mechanisms, respectively. Furthermore, the highest occupied molecular orbital and lowest unoccupied molecular orbital energy gap of the SW-BC defected sheet is highly sensitive to the adsorption process which may be used for the detection of H2S. 相似文献
3.
采用射频磁控溅射技术, 在不同温度下制备了N掺杂Cu2O薄膜.透射光谱分析发现, N掺杂导致Cu2O成为允许的带隙直接跃迁半导体, 并使Cu2O的光学禁带宽度增加.不同温度下沉积的薄膜光学禁带宽度Eg=2.52± 0.03 eV.第一性原理计算表明, N掺杂导致Cu2O的禁带宽度增加了约25%, 主要与价带顶下移和导带底上移有关, 与实验报道基本符合.N的2p电子态分布不同于O原子, 在价带顶附近具有较大的态密度是N掺杂Cu2O变成允许的带隙直接跃迁半导体的根本原因. 相似文献
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Characterizations of B and N heteroatoms as substitutional doping on structure,stability, and aromaticity of novel heterofullerenes evolved from the smallest fullerene cage C20: a density functional theory perspective
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Somayeh Soleimani Amiri Maryam Koohi Behrooz Mirza 《Journal of Physical Organic Chemistry》2016,29(10):514-522
The structural stabilities and electronic properties of C20 fullerene and some its incorporated boron and nitrogen derivatives are probed at B3LYP/AUG‐cc‐pVTZ level of theory. According to density functional theory results, the topology of inserted B or N heteroatoms in [20]‐fullerene perturbs strongly the stability, energy, geometry, charge, polarity, nucleus‐independent chemical shifts, aromaticity, and highest‐occupied molecular orbital and lowest‐unoccupied molecular orbital (HOMO–LUMO) gap of the resulting heterofullerenes. Vibrational frequency (υmin) calculations show that except N10C10, all other BbNnC20‐(b + n) heterofullerenes with b, and n = 0, 4, 5, 8, and 10 are true minima. The calculated band gaps (?EHOMO–LUMO) of B8C12, and N8C12 (2.86 eV), show them the most stable heterofullerenes against electronic excitations. While 10 B substituting in equatorial position increase the conductivity of B10C10 through decreasing its band gaps, 10 N doping in equatorial position enhance stability of N10C10 against electronic excitations via increasing its band gaps. High natural bond orbital and Mulliken charge transfer on the surfaces of B atoms, especially B5N5C10with five B–N bonds in the equatorial position, provokes further investigation on its possible application for hydrogen storage. Nucleus‐independent chemical shift values show that B5N5C10 is the most aromatic species. The calculated heat of atomization per carbon (ΔHat/C) of B8C12 shows it the most thermodynamic stable heterofullerenes of each. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
6.
The N-doping effects on the electronic properties of Cu2O crystals are investigated using density functional theory. The calculated results show that N-doped Cu2O with or without oxygen vacancy exhibits different modifications of electronic band structure. In N anion-doped Cu2O, some N 2p states overlap and mix with the O 2p valence band, leading to a slight narrowing of band gap compared with the undoped Cu2O. However, it is found that the coexistence of both N impurity and oxygen vacancy contributes to band gap widening which may account for the experimentally observed optical band gap widening by N doping. 相似文献
7.
The partial discharge in SF6-insulated equipment produces characteristic decomposition products: SO2 and H2S. The characteristic decomposition products vastly speed up the process of discharge faults. Based on density functional theory (DFT) calculation, single layer Pd-doped MoS2 (Pd-MoS2) is adopted as the adsorbent to adsorb SO2 and H2S to ensure the operational stability of SF6-insulated equipment. The adsorption energy, charge transfer and structure parameters of SF6, H2S, and SO2 adsorption on the Pd-MoS2 monolayer are analysed to find the most stable adsorption structure. The molecular orbital theory, total density of states and partial density of states are studied to analyse the adsorption mechanism. The results show that Pd-MoS2 adsorbent possesses high catalytic activity and excellent adsorption performance to H2S and SO2 by strong chemical adsorption. This study is of great significance to ensure the operational stability of SF6-insulated equipment by removing these characteristic decomposition products. 相似文献
8.
Fullerenes are effective acceptor components with high electron affinity for charge transfer. The significant influences of chemical adsorption of the cations on the electrical sensitivity of pristine C60 and 15-(C2H4O)5/C60 nanocages could be the basis of new generation of electronic sensor design. The density functional theory calculation for alkali and alkaline earth cations detection by pristine C60 and 15-(C2H4O)5/C60 nanocages are considered at B3LYP level of theory with 6–31 G(d) basis set. The quantum theory of atoms in molecules analysis have been performed to understand the nature of intermolecular interactions between the cations and nanocages. Also, the natural bond orbital analysis have been performed to assess the intermolecular interactions in detail. Furthermore, the frontier molecular orbital, energy gap, work function, electronegativity, number of transferred electron (∆N), dipole moment as well as the related chemical hardness and softness are investigated and calculated in this study. The results show that the adsorption of cations (M=Na+, K+, Mg2+ and Ca2+) are exothermic and the binding energy in pristine C60 nanocage and 15-(C2H4O)5/C60 increases with respect to the cations charge. The results also denote a decrease in the energy gap and an increase in the electrical conductivity upon the adsorption process. In order to validate the obtained results, the density of state calculations are employed and presented in the end as well. 相似文献
9.
ABSTRACTUsing density functional theory calculations, we investigate the gas sensing performance of B-, N-doped and BN-codoped C60 fullerenes towards NO and NO2 molecules. The calculated adsorption energies and net charge-transfer values indicate that NO and NO2 molecules have a stronger interaction with the BN-codoped fullerenes compared to the B- or N-doped ones. It is also found that the electronic properties of the BN-codoped C60 exhibit a larger sensitivity towards NO and NO2 molecules. An increase in the concentration of doped/co-doped B and N atoms tends to weaken the gas sensing ability of these systems. 相似文献
10.
对O原子采用6-311++G*基组,Zr原子采用aug-cc-pVTZ-PP基组,利用密度泛函(B3P86)方法优化得到了ZrO2分子的稳定构型,并研究了不同外电场(0—0.025 a.u.)作用下ZrO2基态分子键长、能量、电荷分布、偶极矩和能级的变化规律.在优化构型的基础上,利用含时密度泛函(TD-B3P86)方法研究了ZrO2分子在外电场作用下前6个激发态的激发能、跃迁波长和振子强度的激发特性.研究结果表明:随着电场强度的增大,Zr—2O的键长增大,而Zr—3O的键长均匀减少,总能量降低,偶极矩增大;最高占据轨道能量基本保持不变,最低未占据轨道和能隙均减小.电场的增大使得激发能减小,各个激发态跃迁波长均发生不同程度的红移现象,因而,利用外电场可以控制ZrO2的发光光谱范围在可见-红外区域扩展. 相似文献
11.
Y. F. Ouyang D. M. Zhai J. Fang P. Xiang Y. Du Y. H. He 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):629-641
The geometries and electronic structural properties of AB and ABC (A, B, C = Al, Fe, Zr, Ce) microclusters have been systematically
investigated by using a hybrid density-functional method (B3LYP) approach. The spectroscopic constants of ground-state AB
and ABC (A, B, C = Al, Fe, Zr, Ce) are obtained, and are found to be in agreement with other available experimental and theoretical
results. The calculated gaps between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO)
are clearly changed when X is doped into the AB dimers (X = Al, Fe, Zr, Ce). The calculated results indicate that a triangular
form with D3h, C2v or Cs symmetry is the most stable for the corresponding ABC trimers, and, in addition, the possible isomers (linear structure)
with D∞h or C∞v symmetry of three-atom clusters were found to be of higher energies. We conclude that AlFe and Al2Fe have the highest chemical stability of all the AB dimers and ABC trimers, respectively, due to the high HOMO-LUMO gap.
We also find that the binding energy of Ce3 is the largest in magnitude among all ABC (A, B, C = Al, Fe, Zr, Ce) trimers, as is the case with Ce2 among all AB (A, B, C = Al, Fe, Zr, Ce) dimers. The most stable geometry, charge transfer and possible dissociation channels
are also discussed. 相似文献
12.
C. H. Yao S. F. Zhao J. R. Li Y. W. Mu J. G. Wan M. Han G. H. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(2):197-205
The lowest-energy geometries and electronic-structure properties have been
obtained for AlnHn (n=1-10) clusters within the
density-functional theory using the generalized gradient approximation for
the exchange correlation potential. The resulting geometries show that the
hydrogen atoms tend to occupy outside positions and no hollow positions are
found. The subunit Aln of AlnHn (n=1-5) have little
distortion, in comparison with corresponding pure Aln cluster, whereas
the subunit Aln have large distortion from n=6. The stability has been
investigated by analyzing the binding energy per atom and the second
difference in energy, indicating that Al8H8 exhibit higher
stability than others. The bonding property has been analyzed by calculating
the Mulliken charges and Al–H distances. The calculated energy gap between
the highest occupied molecular orbital and the lowest unoccupied molecular
orbital (HOMO-LUMO), the vertical ionization potential, and the vertical
electron affinity also confirm that Al8H8 is a stable cluster. The
density of states (DOS) shows that AlnHn exhibit changes from
molecular-like (Al1H1) to band-like structure (Al10H10)
as n increases. 相似文献
13.
Min LiJun-ying Zhang Yue ZhangGuo-feng Zhang Tian-min Wang 《Applied Surface Science》2011,257(24):10710-10714
First-principles calculation on the basis of the density functional theory (DFT) and generalized gradient approximation have been applied to study the adsorption of H2 on the stoichiometric O-terminated Cu2O (1 1 1), Cu2O (1 1 1)-CuCUS and Cu-terminated Cu2O (1 1 1) surfaces. The optimal adsorption position and orientation of H2 on the stoichiometric O-terminated Cu2O (1 1 1) surface and Cu-terminated Cu2O (1 1 1) surface were determined and electronic structural changes upon adsorption were investigated by calculating the Local Density of States (LDOS) of the CuCUS 3d and CuCUS 4s of stoichiometric O-terminated Cu2O (1 1 1) surface. These results showed that H2 molecule adsorption on CuCUS site parallel to stoichiometric O-terminated Cu2O (1 1 1) surface and H2 molecule adsorption on Cu2 site parallel to Cu-terminated Cu2O (1 1 1) surface were the most favored, respectively. The presence of surface copper vacancy has a little influence on the structures when H2 molecule adsorbs on CuCSA, OCUS and OCSA atoms and the H2 molecule is only very weakly bound to the Cu2O (1 1 1)-CuCUS surface. From the analysis of stoichiometric O-terminated Cu2O (1 1 1) Local Density of States, it is observed that CuCUS 3d orbital has moved to a lower energy and the sharp band of CuCUS 4s is delocalized when compared to that before H2 molecule adsorption, and overlapped substantially with bands due to adsorbed H2 molecule. The Mulliken charges of H2 adsorption on CuCUS site showed that H2 molecule obtained electron from CuCUS which was consistent with the calculated electronic structural changes upon H2 adsorption. 相似文献
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15.
Chao Zhang Yongzhong Jia Yan Jing Ying Yao Jun Ma Jinhe Sun 《Physica B: Condensed Matter》2012,407(24):4649-4654
The electronic structures and optical properties of N-doped, S-doped and N/S co-doped SrTiO3 have been investigated on the basis of density functional theory (DFT) calculations. Through band structure calculation, the top of the valence band is made up of the O 2p states for the pure SrTiO3. When N and S atoms were introduced into SrTiO3 lattice at O site, the electronic structure analysis shows that the doping of N and S atoms could substantially lower the band gap of SrTiO3 by the presence of an impurity state of N 2p on the upper edge of the valence band and S 2p states hybrid with O 2p states, respectively. When the N/S co-doped, the energy gap has further narrowing compared with only N or S doped SrTiO3. The calculations of optical properties also indicate a high photo response for visible light for N/S co-doped SrTiO3. Besides, we find a new impurity state which separates from the O 2p states could improve the photocatalytic efficiency and we also propose a model for light electron-hole transportation which can explain the experiment results well. All these conclusions are in agreement with the recent experimental results. 相似文献
16.
姚利花 《原子与分子物理学报》2018,35(6)
采用基于密度泛函理论的第一性原理方法,研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为。主要研究了三种石墨烯:本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯。结果表明,与本征石墨烯相比,B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密度、态密度和储钠量方面表现出很大的差异。B掺杂的石墨烯对Na原子的吸附能是-1.93 eV,约为本征石墨烯对Na原子吸附能的2.7倍;与本征石墨烯相比,N掺杂的石墨烯对Na原子的吸附能明显增大。态密度计算结果表明,Na原子与B掺杂的石墨烯中的B原子发生轨道杂化,而本征石墨烯和N掺杂的石墨烯中不存在轨道杂化现象。B掺杂的石墨烯对Na原子的吸附量是3个,与本征石墨烯相比显著提高。因此,B掺杂的石墨烯有望成为一种新型的储钠材料。 相似文献
17.
姚利花 《原子与分子物理学报》2017,34(3):569-576
采用基于密度泛函理论的第一性原理方法,研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为.主要研究了三种石墨烯:本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯.结果表明,与本征石墨烯相比,B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密度、态密度和储钠量方面表现出很大的差异.B掺杂的石墨烯对Na原子的吸附能是-1.93 e V,约为本征石墨烯对Na原子吸附能的2.7倍;与本征石墨烯相比,N掺杂的石墨烯对Na原子的吸附能明显增大.态密度计算结果表明,Na原子与B掺杂的石墨烯中的B原子发生轨道杂化,而本征石墨烯和N掺杂的石墨烯中不存在轨道杂化现象.B掺杂的石墨烯对Na原子的吸附量是3个,与本征石墨烯相比显著提高.因此,B掺杂的石墨烯有望成为一种新型的储钠材料. 相似文献
18.
In this paper, the density functional theory has been used to perform a comparative theoretical study of water monomer, dimer, trimer, and bilayer adsorptions on the Be(0001) surface. In our calculations, the adsorbed water molecules are energetically favoured adsorbed on the atop sites, and the dimer adsorption is found to be the most stable with a peak adsorption energy of ~437 meV. Further analyses have revealed that the essential bonding interaction between the water monomer and the metal substrate is the hybridization of the water 3a1-like molecular orbital with the (s, pz) orbitals of the surface beryllium atoms. While in the case of the water dimer adsorption, the 1b1-like orbital of the H2O molecule plays a dominant role. 相似文献
19.
Ali Shokuhi Rad Sahand Sadeghi Shabestari Seyed Ahmad Jafari Mohammad Reza Zardoost Ali Mirabi 《Molecular physics》2013,111(11):1756-1762
ABSTRACTThis work reports the physisorption of carbon monoxide (CO) on the surface of N-doped graphene. To study the adsorption of CO on N-doped graphene, some quantum chemical calculations were used through density functional theory. Based on our results, it can be found that the CO molecule could be adsorbed on the surface of N-doped graphene physically with the adsorption energies (Eads) of ?2.9 and ?0.8 kcal mol?1 (depends on the kind of configuration) while positive adsorption energies were calculated upon adsorption of CO on pristine graphene. We used the charge analysis for calculation of the net transferred charge of adsorbed CO on pristine and N-doped graphene sheets to evaluate the sensing ability of surface. The global indices of reactivity were calculated from the differences of the lowest unoccupied molecular orbital and highest occupied molecular orbital energies. Graphs for density of states point to some orbital hybridisation between CO molecule and N-doped graphene. Consequently, the N-doped graphene transforms the existence of CO molecules into electrical signal, and it may be potentially used as a sensor for CO. 相似文献
20.
Guodong Tang Jianying Zhao Zhengjing Jiang Shanshan Kou Xuehai Ju Changmei Wei 《Optics and Spectroscopy》2012,113(3):240-258
A series of Schiff-bases chromophores containing imine or double C=C bond linkers between the donor and acceptor have been studied by first-principles calculations. The molecular structures, electronic properties and second order nonlinearities were investigated by DFT and ab initio methods. The optimized structural parameters of these Schiff-base derivates showed that these compounds are stable. The results of TD-DFT calculations indicate that the derivatives with the heterocyclic and imine linker have a red shift absorption compared to derivatives with the double C=C or N=N bonds. The analysis of the frontier molecular orbitals indicates that the CN group and the heterocycle linked by the CN or imine group has contribution to the LUMO orbital while the groups N(CH3)2 and the benzene ring linked by the double C=C or N=N bond have contribution to the HOMO orbital. The CN and the heterocyclic acceptors enable the derivatives to have a larger first static hyperpolarizability. However, the compounds 3-{4-[(4-Dimethylamino-phenylimino)-methyl]-pyridin-1-yl}-propanel-1-sulfonoperoxoic acid and 3-{4-[(4-Dimethylamino-phenylimino)-methyl]-quinolin-1-yl}propanel-1-sulfonoperoxoic acid with a substituent also have large first static hyperpolarizabilities due to the overwhelming contributions of electron density of the group to the HOMO orbital, that is, the HOMO orbital were constituted by the SO 3 ? group only. In order to understand the influence of the energy gap (??E) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (??E) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap the larger the first static hyperpolarizability. The present study demonstrated that these compounds which have pure C=N double bond and heterocyclic substitution groups may have potential applications in the development of NLO materials. 相似文献