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1.
Density functional theory B3LYP method with 6‐31G* basis set has been used to optimize the geometries of the catechin, water and catechin‐(H2O)n complexes. The vibrational frequencies have been studied at the same level to analyze these complexes. Six and eleven stable structures for the catechin‐H2O and catechin‐(H2O)2 have been found, respectively. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes corrected by basis set superposition error, are from ?13.27 to ?83.56 kJ/mol. All calculations also indicate that there are strong hydrogen‐bonding interactions in catechin‐water complexes. The strong hydrogen‐bonding contributes to the interaction energies dominantly. The O–H stretching motions in all the complexes are red‐shifted relative to that of the monomer. 相似文献
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{[Cu^Ⅱ(Hpb)(mal)]H=O}n (Hpb=2-2'-pyridylbenzimidazole, mal=maleic acid) is a helical chain-like polymer complex. In order to investigate the electronic structure of the complex, the monomer Cu^Ⅱ(Hpb)(mal) was obturated with different functional groups respectively. For these selective segments, the geometry optimizations were conducted by using hybrid DFT (B3LYP)methods to find that the structure obturated with H2O was better consistent with the experiment, and then this model would be used to latter calculations, such as the frontier molecular orbital and the NBO charge population analysis. In addition the magnetic behaviors of this complex were analyzed by experiments and the weak antiferromagnetic couple between copper(Ⅱ) ions was observed. The exchange coupling constant was calculated by DFT based on the spin broken symmetry formalism. The calculated coupling constants were in good agreement with the experimental data. 相似文献
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Gang Lv Fadong Wei Hui Jiang Yanyan Zhou Xuemei Wang 《Journal of Molecular Structure》2009,915(1-3):98-104
Density functional B3LYP method with 6-31++G** basis set is applied to optimize the geometries of the luteolin, water and luteolin–(H2O)n complexes. The vibrational frequencies are also studied at the same level to analyze these complexes. We obtained four steady luteolin–H2O, nine steady luteolin–(H2O)2 and ten steady luteolin–(H2O)3, respectively. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) are used to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes corrected by basis set superposition error, are within −13.7 to −82.5 kJ/mol. The strong hydrogen bonding mainly contribute to the interaction energies, Natural bond orbital analysis is performed to reveal the origin of the interaction. All calculations also indicate that there are strong hydrogen bonding interactions in luteolin–(H2O)n complexes. The OH stretching modes of complexes are red-shifted relative to those of the monomer. 相似文献
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Milan Z. Milovanović Stanka V. Jerosimić 《International journal of quantum chemistry》2014,114(3):192-208
We present theoretical investigation of the structural characteristics and stabilities of neutral and positively charged LinI (n = 2‐6) species. The structural isomers were found by using a randomized algorithm to search for minima structures, followed by B3LYP optimizations; the single‐point RCCSD(T)/cc‐pwCVTZ(‐PP) calculations were performed in order to compute relative energies, binding energies per atom, adiabatic and vertical ionization energies, and dissociation energies. Stability was compared to the pure lithium clusters; there is a typical odd‐even alternation; iodine doped clusters are more stable than pure lithium clusters. Lithium “cage” transfers its valence electron to the iodine atom to form neutral and cationic clusters. An electron departures the lithium cage upon ionization. An important reason for the larger stability of closed‐shell species is the existence of the HOMO 3c/2e natural bond orbitals. © 2013 Wiley Periodicals, Inc. 相似文献
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Xiao‐Qing Wang Zhen‐Yi Jiang Jun‐Qian Li Qing‐Li He San‐Yan Chu 《International journal of quantum chemistry》2011,111(1):182-190
Geometric structures, electronic properties, and stabilities of small Zrn and Zr (n = 2–10) clusters have been investigated using density functional theory with effective core potential LanL2DZ basis set. For both neutral and charged systems, several isomers and different multiplicities were studied to determine the lowest energy structures. Many most stable states with high symmetry were found for small Zrn clusters. The most stable structures and symmetries of Zr clusters are the same as the neutral ones except n = 4 and 7. We found that the clusters with n > 3 possess highly compact structures. The clusters are inclined to form the caged‐liked geometry containing pentagonal structures for n > 8, which is in favor of energy. From the formation energy and second‐order energy difference, we obtained that 2‐, 5‐, 7‐atoms of neutral and 4‐, 7‐atoms cationic clusters are the magic numbers. Furthermore, the highest occupied molecular orbital‐lowest unoccupied molecular orbital gaps display that the Zr3, Zr6, Zr, and Zr are more stable in chemical stability. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
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Chuanyun Xiao Sven Krüger Thomas Belling Markus Mayer Notker Rsch 《International journal of quantum chemistry》1999,74(4):405-416
Relativistic effects on the properties of small neutral Pdn species (n=1, 2, 4) and Pd2− have been examined for the first time at the all‐electron level by performing scalar‐relativistic and nonrelativistic density functional calculations using a gradient‐corrected density functional. Relativistic effects are found to be important: They lead to a contraction of bond lengths, increase of vibrational frequencies, and a significant enhancement of binding energies. While relativistic effects are quite uniform for several states of Pd4, they vary for the states examined for Pd2, leading to a change of ground state due to relativity. The calculated relativistic properties of Pd2 and Pd2− are in good agreement with available experimental data from mass spectrometry and photoelectron spectroscopy. For Pd4 three‐dimensional structures are found to be preferred to planar ones and many nearly isoenergetic isomers exist. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 74: 405–416, 1999 相似文献
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在MP2/6-311++G**水平上优化乙烯酮自由基与LiX(X=F,Cl,Br)形成锂键复合物.当卤素的电负性很强(如F元素),使得Li原子处于缺电子状态,此时,电子给体会把电子偏移向锂,形成共价性较强的锂键.而当卤素的电负性减弱时,锂键中主要成分逐渐变为离子键,并且此时锂键性质还要受电子给体影响.另外,由于HCCO为缺电子结构,电负性较弱且体积较大的卤素中的孤对电子会与HCCO之间通过静电相互作用,使得HCCO…Li—X键夹角变小,接近120°.锂键性质对HCCO…LiX(X=F,Cl,Br)复合物中Li—X的伸缩振动频率有直接影响.当锂键表现为共价性时,该频率红移,而当锂键表现为离子性时,该频率蓝移.但是,由于Cl的电负性与O的接近,C的电负性与Br接近所以,在O…Li…Cl和C…Li…Br中容易形成共振结构,导致远大于在其他复合物中的红移. 相似文献
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Investigation of substituent effects in aerogen‐bonding interaction between ZO3 (Z=Kr,Xe) and nitrogen bases 下载免费PDF全文
Mehdi D. Esrafili Soheila Asadollahi Mahshad Vakili 《International journal of quantum chemistry》2016,116(16):1254-1260
The substituent effects in aerogen bond interactions between ZO3 (Z = Kr, Xe) and different nitrogen bases are studied at the MP2/aug‐cc‐pVTZ level of theory. The nitrogen bases include the sp bases NCH, NCF, NCCl, NCBr, NCCN, NCOH, NCCH3 and the sp3 bases NH3, NH2F, NH2Cl, NH2Br, NH2CN, NH2OH, and NH2CH3. The nature of aerogen bonds in these complexes is analyzed by means of molecular electrostatic potential, electron localization function, quantum theory atoms in molecules, noncovalent interaction index, and natural bond orbital analyses. The interaction energy (Eint) ranges from ?4.59 to ?9.65 kcal/mol in the O3Z···NCX complexes and from ?5.30 to ?13.57 kcal/mol in the O3Z···NH2X ones. The dominant charge‐transfer interaction in these complexes occurs across the aerogen bond from the nitrogen lone‐pair (nN) of the Lewis base to the σ*Z‐O antibonding orbital of the ZO3. Besides, the formation of aerogen bond tends to decrease the 83Kr or 131Xe chemical shielding values in these complexes. © 2016 Wiley Periodicals, Inc. 相似文献
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Luis Padilla‐Campos 《International journal of quantum chemistry》2009,109(6):1357-1367
A theoretical study of the adsorption of molecular oxygen on small bimetallic LimCun (m, n ≤ 4) clusters was carried out using density functional methods, and it was compared with the adsorption of O2 on copper (Cun, n ≤ 8) clusters. The study of O2‐LimCun system is important to understand the promotion effects of the alkali atoms on the copper surface participating in the catalytic processes. Adsorption energies ranging from 7.9 to 51 kcal/mol were found, which represented values over 30% to those calculated for the adsorption of O2 on copper clusters in a previous study. Thus, the reactivity of molecular oxygen on bimetallic clusters is more favorable with high tendency being in favor of the dissociation of the O2 molecule. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 相似文献
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Comprehensive study of threonine adsorption on carbon nanotube: A dispersion complemented density functional theory‐based treatment 下载免费PDF全文
Cuihong Wang Yue Jiang Guangwu Yang 《International journal of quantum chemistry》2015,115(22):1606-1612
The interaction mechanism of threonine (Thr) on the sidewall of (8, 8) single‐walled carbon nanotubes (CNTs) was investigated by density functional tight‐binding method. All the functional groups of Thr were used to interact with the surface of CNT. The structural parameters were analyzed to identify the noncovalent interactions, and the binding energy and strain energy were used to indicate the binding properties. We found that the CH/π interactions play more important roles than NH/π and OH/π interactions in stabilizing the complex structures. Furtherly, the charge transfer properties, density of states (DOS) and partial density of states, and highest occupied molecular orbitals and lowest unoccupied molecular orbitals were also studied to illustrate the adsorbed interactions. The results show that the DOS structure of CNT could be modified by the adsorption of Thr, and, therefore, the conductivity of CNT will be improved by introducing proper amino acids. Our data should be helpful for the design of biocompatible molecules for CNT modification. © 2015 Wiley Periodicals, Inc. 相似文献
12.
Guangfen Wu Mingli Yang Xingyu Guo Jinlan Wang 《Journal of computational chemistry》2012,33(23):1854-1861
Using gradient‐corrected density functional theory, we have comparatively studied the adsorption properties of diatomic molecules N2 and NO on vanadium clusters up to 13 atoms. Spontaneous dissociation is found for N2 adsorbing on Vn with n = 4–6, 12, and for NO with n = 3–12, respectively, whereas for the rest of the clusters, N2 (NO) molecularly adsorbs on the cluster for all the possible sites. The incoming N2 retains the magnetism of Vn except for V2 and V6 whose moments are quenched from 2 μB to zero. Consequently, the moments of VnN2 (n = 2–13) show even/odd oscillation between 0 and 1 μB. On the adsorption of NO, the magnetic moments of Vn with closed electronic shell are raised to 1 μB at n = 4, 8, and 10, and 3 μB at n = 12, whereas for open shell clusters, their magnetic moments increase for n = 5 and 9 and decrease for n = 2, 3, 5–7, 11, and 13 by 1 μB. These findings are rationalized by combinatory analysis from several aspects, for example, the geometry and stability of bare clusters, charge transfer induced by the adsorption, feature of frontier orbitals, and spin density distribution. © 2012 Wiley Periodicals, Inc. 相似文献
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Ignacio Viciano Slawomir Berski Sergio Martí Juan Andrés 《Journal of computational chemistry》2013,34(9):780-789
The electronic structure of iron‐oxo porphyrin π‐cation radical complex Por·+FeIV?O (S? H) has been studied for doublet and quartet electronic states by means of two methods of the quantum chemical topology analysis: electron localization function (ELF) η(r) and electron density ρ(r). The formation of this complex leads to essential perturbation of the topological structure of the carbon–carbon bonds in porphyrin moiety. The double C?C bonds in the pyrrole anion subunits, represented by pair of bonding disynaptic basins Vi=1,2(C,C) in isolated porphyrin, are replaced by single attractor V(C,C)i=1–20 after complexation with the Fe cation. The iron–nitrogen bonds are covalent dative bonds, N→Fe, described by the disynaptic bonding basins V(Fe,N)i=1–4, where electron density is almost formed by the lone pairs of the N atoms. The nature of the iron–oxygen bond predicted by the ELF topological analysis, shows a main contribution of the electrostatic interaction, Feδ+···Oδ?, as long as no attractors between the C(Fe) and C(O) core basins were found, although there are common surfaces between the iron and oxygen basines and coupling between iron and oxygen lone pairs, that could be interpreted as a charge‐shift bond. The Fe? S bond, characterized by the disynaptic bonding basin V(Fe,S), is partially a dative bond with the lone pair donated from sulfur atom. The change of electronic state from the doublet (M = 2) to quartet (M = 4) leads to reorganization of spin polarization, which is observed only for the porphyrin skeleton (?0.43e to 0.50e) and S? H bond (?0.55e to 0.52e). © 2012 Wiley Periodicals, Inc. 相似文献
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Yuhui Qu Wanyong Ma Xiufang Bian Hongwei Tang Weixing Tian 《International journal of quantum chemistry》2006,106(4):960-967
The geometry, electronic configurations, harmonic vibrational frequencies, and stability of the structural isomers of boron phosphide clusters have been investigated using density functional theory (DFT). CCSD(T) calculations show that the lowest‐energy structures are cyclic (IIt, IVs) with Dnh symmetry for dimers and trimers. The caged structure for B4P4 lie higher in energy than the monocyclic structure with D2d symmetry (VIs). The B–P bond dominates the structures for many isomers, so that one preferred dissociation channel is loss of the BP monomer. The hybridization and chemical bonding in the different structures are also discussed. Comparisons with boron nitride clusters, the ground state structures of BnPn (n = 2, 3) clusters are analogous to those of their corresponding BnNn (n = 2, 3) counterparts. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
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Jiao Sun Wen‐Cai Lu Hong Wang Li‐Zhen Zhao Ze‐ Sheng Li Chia‐Chung Sun 《International journal of quantum chemistry》2007,107(9):1915-1924
The structural properties of neutral and ionic AlnO2 (n = 1–10) clusters have been systematically investigated using the density functional method B3LYP with a standard 6‐311+G(d) basis set. The calculated results show that in the AlnO, AlnO2, and AlnO (n ≥ 3) clusters, O atoms tend to penetrate into the aluminum clusters with some Al atoms moving outward. The binding energies and natural charges populations indicate that the oxygen‐etching is generally stronger in the order Al < Aln < Al for n < 3, and Al > Aln > Al for n ≥ 3. To further understand the mechanism of interaction between Al and O2, the adsorption of O2 on the Al(111) surface was studied using the density functional theory with plane wave pseudopotential method. The calculated results are consistent with the experimental observation that the O2 molecule would dissociate on the Al(111) surface and be adsorbed in adjacent hollow sites, forming a local structure of Al3O–Al3O. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
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Treatment of delocalized electron transfer in periodic and embedded cluster DFT calculations: The case of Cu on ZnO (10
0) 下载免费PDF全文
Matti Hellström Daniel Spångberg Kersti Hermansson 《Journal of computational chemistry》2015,36(32):2394-2405
We assess the consequences of the interface model—embedded‐cluster or periodic‐slab model—on the ability of DFT calculations to describe charge transfer (CT) in a particularly challenging case where periodic‐slab calculations indicate a delocalized charge‐transfer state. Our example is Cu atom adsorption on ZnO(10 0), and in fact the periodic slab calculations indicate three types of CT depending on the adsorption site: full CT, partial CT, and no CT. Interestingly, when full CT occurs in the periodic calculations, the calculated Cu atom adsorption energy depends on the underlying ZnO substrate supercell size, since when the electron enters the ZnO it delocalizes over as many atoms as possible. In the embedded‐cluster calculations, the electron transferred to the ZnO delocalizes over the entire cluster region, and as a result the calculated Cu atom adsorption energy does not agree with the value obtained using a large periodic supercell, but instead to the adsorption energy obtained for a periodic supercell of roughly the same size as the embedded cluster. Different density functionals (of GGA and hybrid types) and basis sets (local atom‐centered and plane‐waves) were assessed, and we show that embedded clusters can be used to model Cu adsorption on ZnO(10 0), as long as care is taken to account for the effects of CT. © 2015 Wiley Periodicals, Inc. 相似文献
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The results of theoretical studies on structures and energetics are presented for proton-bound complexes N2H+–XH, N2H+–X2, and N2H+–XY(YX) (X=Y=F, Cl, and Br). In all the monocations complexes, the halogen atom shares a proton with N2. The calculated energetic results show that the stability decreases when descending in the corresponding periodic table column. The possible proton transfer dissociation processes of N2H++XH, N2H++X2, and N2H++XY systems into XH2+, X2H+, XYH+, and YXH+ and molecular N2 are calculated to be endothermic for share of the processes. The NBO results show that the largest intermolecular charge transfer is found in the Br bonded complexes. 相似文献
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Benjamí Martorell Anna Clotet Jordi Fraxedas 《Journal of computational chemistry》2010,31(9):1842-1852
We have studied the adsorption properties of a charge donor organic molecule, tetrathiafulvalene (TTF), on the (110) surfaces of silver and gold by means of the generalized gradient approach of the density functional theory using periodic slab models. This molecule is the core building block of a host of molecular materials exhibiting extremely reach phase diagrams with a variety of ground states. The interfaces formed with metallic surfaces have received only limited attention, despite of their relevance. We have determined the stable adsorption sites for two unit cells representing high and low coverage, which are determinant for the adsorption properties of TTF on the surface. The preferential chemisorption is via the direct interaction of sulfur atoms with the Ag or Au atoms on top sites. All adsorbed TTF are more stable than gas phase TTF. The simulation of the vibrational spectra has permitted us to find the fingerprints of these structures to characterize them on this surface. The donor nature of TTF induces charge transfer to the metallic surfaces. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
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H/D isotope effect on charge‐inverted hydrogen‐bonded systems: Systematic classification of three different types in H3XH…YH3 (X = C,Si, or Ge,and Y = B,Al, or Ga) with multicomponent calculation 下载免费PDF全文
Three different H/D isotope effect in nine H3XH(D)…YH3 (X = C, Si, or Ge, and Y = B, Al, or Ga) hydrogen‐bonded (HB) systems are classified using MP2 level of multicomponent molecular orbital method, which can take account of the nuclear quantum nature of proton and deuteron. First, in the case of H3CH(D)…YH3 (Y = B, Al, or Ge) HB systems, the deuterium (D) substitution induces the usual H/D geometrical isotope effect such as the contraction of covalent R(C? H(D)) bonds and the elongation of intermolecular R(H(D)…Y) and R(C…Y) distances. Second, in the case of H3XH(D)…YH3 (X = Si or Ge, and Y = Al or Ge) HB systems, where H atom is negatively charged called as charge‐inverted hydrogen‐bonded (CIHB) systems, the D substitution leads to the contraction of intermolecular R(H(D)…Y) and R(X…Y) distances. Finally, in the case of H3XH(D)…BH3 (X = Si or Ge) HB systems, these intermolecular R(H(D)…Y) and R(X…Y) distances also contract with the D substitution, in which the origin of the contraction is not the same as that in CIHB systems. The H/D isotope effect on interaction energies and spatial distribution of nuclear wavefunctions are also analyzed. © 2015 Wiley Periodicals, Inc. 相似文献