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1.
Optimized molecular structures, electron affinities, and IR-active vibrational frequencies have been predicted using five different hybrid Hartree–Fock/density functional theory (DFT) methods for a series of mono-, di-substituted SF6 compounds. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. These methods have been carefully calibrated [J.C. Rienstra-Kiracofe, G.S. Tschumper, H.F. Schaefer, S. Nandi, G.B. Ellison, Chem. Rev. 102 (2002) 231]. The equilibrium configurations of the anions and are found to be a zigzag geometry with 2A electronic state. Three different types of the neutral-anion energy separation reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities of the mono-, di-substituted SF6 compounds obtained at the KMLYP function are 1.48 eV (SF6), 3.20 eV (SF5Cl), 3.49 eV (SF5Br), 1.59 eV (SF5CF3), 3.21 eV (CF3SF4Cl), 3.59 eV (CF3SF4Br), 1.36 eV (CF3SF4CH3), 2.32 eV (CF3SF4CF3), respectively. 相似文献
2.
Meng Zhang Li-Ming He Li-Xia Zhao Xiao-Juan Feng Wei Cao You-Hua Luo 《Journal of Molecular Structure》2009,911(1-3):65-69
The geometries, electronic, and magnetic properties of the Au7Hn (n = 1–10) clusters have been systematically investigated by using relativistic all-electron density functional theory with generalized gradient approximation. It is found that the Au7 on the whole retains its triangle structure after hydrogen atoms adsorption and adsorbing hydrogen atoms can stabilize the Au7 structure. The Au7H7 cluster is much higher stability than the neighboring clusters. The pronounced even–odd alternation of the magnetic moments is observed in the Au7Hn systems indicating Au7Hn clusters possess tunable magnetic properties by adding even or odd number of H atoms. 相似文献
3.
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
4.
All-electron scalar relativistic calculations have been performed to investigate the electronic structures of neutral gold clusters (Aun, n = 2–13) in the gas phase using density functional theory with the generalized gradient approximation. Full geometry optimizations of topologically different clusters and clusters belonging to different symmetry groups have been carried out. Binding energies, ionization potentials, electron affinities, and chemical hardness values are calculated and they are found to be comparable with the available experimental and theoretical results. The most stable structure of each of the cluster has a two-dimensional planar configuration. A three dimensional distorted Y shaped structure (4b) for Au4, a tri-capped triangle (6b), a chair (6f), and a see-saw structure (6j) for Au6, an eclipsed sandwich structure (7g) for Au7, a condensed trigonal bipyramid (9e) and a boat shaped structure (9f) for Au9, a staggered sandwich (11c) and an eclipsed sandwich structure (11d) for Au11, a ladderane structure (12d) for Au12, and a staggered (13d) and a distorted sandwich structure (13e) for Au13 are characterized for the first time in this work. 相似文献
5.
With replacement of N atoms by CH groups in the most stable chain isomer of N8H8, 34 possible isomers of Nn(CH)8−nH8 (n = 0–7) have been designed and optimized at the B3LYP/6-311++G** level of theory. The natural bond orbital (NBO) and atoms in molecules (AIM) analysis are carried out to study the bonding nature and relative stabilities of these conformers. G3MP2 method is applied to calculate energies and heats of formation. The results indicate that the hyperconjugation effect from lone pairs of nitrogen atoms to germinal C–N bonds is the major factor which caused the change of the C–N bond length. With the more replacement of nitrogen atoms by CH groups, the heats of formation of the isomers of Nn(CH)8−nH8 (n = 0–7) decrease gradually, but the energies increase linearly. 相似文献
6.
Rui Li Li-Hua Gan Li Lin Jian-Qiang Zhao Jian Liu 《Journal of Molecular Structure》2009,911(1-3):75-80
To gain an insight into the structures and stability of F4F6-(BN)n polyhedrons with alternation of B and N atoms, a density functional theory study was performed on all isomers of F4F6-(BN)n polyhedrons with n between 10 and 22. The calculation results demonstrate that the lowest energy isomers do not contain B44 bonds (the bonds shared by two squares) and the energies of those isomers containing B44 bonds increase with the number of B44 bonds linearly, indicating that the energetically favored structures of F4F6-(BN)n polyhedrons satisfy the isolated square rule and square adjacency penalty rule. The structural analysis reveals that the stability is determined by the pyramidalization of B and N atoms at the square–square fusion. The binding energy is fitted to the numbers of edges and a model is proposed for predicting the relative stability of these B–N polyhedral molecules. 相似文献
7.
Geometries, electronic states, and electron affinities of GamPn and GamP (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 with the basis of a 6‐311+G(2df) one‐particle basis set. The geometries are fully optimized with each DFT method independently. 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 method for predicting molecular structures was found to be BLYP, while other methods generally underestimated bond lengths. The most reliable adiabatic electron affinities and vertical detachment energy, obtained at the BP86 and B3LYP level of theory, are predicted to be 2.22 and 2.10 eV (GaP), 2.51 and 2.46 eV (Ga2P), 1.86 and 1.94 eV (GaP2), 1.96 and 2.27 eV (GaP3), 1.76 and 1.99 eV (Ga3P), 1.79 and 2.14 eV (Ga2P2), 2.85 and 3.67 eV (GaP4), 2.08 and 2.10 eV (Ga4P), 2.90 and 3.17 eV (Ga2P3), and 2.70 and 3.37 eV (Ga3P2), respectively. Those for Ga2P, Ga3P, Ga2P2, Ga4P, GaP4, Ga2P3, and Ga3P2 are in good agreement with experiment, but the predicted EAad values for GaP, Ga2P, GaP2, and GaP3 are larger than the available experimental values. For the vibrational frequencies of the GamPn series, the B3LYP method produces good predictions with the average error only ~10 cm?1 from available experimental and theoretical values. The other three methods overestimate or underestimate the vibrational frequencies, with the worst predictions given by the BLYP method. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
8.
Guoliang Li Xiaohong Li Chaoyang Wang Guozheng Ma 《Journal of Molecular Structure》2009,910(1-3):50-55
The lithium-doped carbon clusters LiCn, , and (n = 1–10) have been investigated systemically with density functional theory (DFT) method at the B3LYP/6-311+G* level. According to the total energies of different kinds of isomers, the LiCn, , and (n = 1–10) clusters have Li-terminated linear ground states structures, except for LiC2, LiC3, , and (n = 4–6). The incremental binding energies are evaluated to elucidate the stabilities of the clusters with different numbers of carbon atoms for neutral molecules, cations, and anions, respectively. Clear even–odd alternation effects are observed for the stability of the cationic clusters and anionic clusters, while for neutral LiCn clusters the alternation effect is less pronounced. Similarly, the ionization potentials and electron affinities of LiCn also express an obvious parity alternation. In addition, the most favorable dissociation channels are acquired according to the fragmentation energies accompanying various pathways. 相似文献
9.
Hongyan Wang Yaoming Xie R. Bruce King Henry F. Schaefer III 《Journal of organometallic chemistry》2008,693(20):3201-3212
Binuclear cycloheptatrienylchromium carbonyls of the type (C7H7)2Cr2(CO)n (n = 6, 5, 4, 3, 2, 1, 0) have been investigated by density functional theory. Energetically competitive structures with fully bonded heptahapto η7-C7H7 rings are not found for (C7H7)2Cr2(CO)n structures having two or more carbonyl groups. This result stands in contrast to the related (CnHn)2M2(CO)n (M = Mn, n = 6; M = Fe, n = 5; M = Co, n = 4) systems. Most of the predicted (C7H7)2Cr2(CO)n structures have bent trihapto or pentahapto C7H7 rings and CrCr distances in the range 2.4–2.5 Å suggesting formal triple bonds. In some cases rearrangement of the heptagonal C7H7 ring to a tridentate cyclopropyldivinyl or tridentate bis(carbene)alkyl ligand is observed. In addition structures with CO insertion into the C7H7–Cr bond are predicted for (C7H7)2Cr2(CO)n (n = 6, 4, 2). The global minima found for the (C7H7)2Cr2(CO)n derivatives for n = 6, 5, and 4 are (η5-C7H7)(OC)2CrCr(CO)4(η1-C7H7), (η3-C7H7)(OC)2CrCr(CO)3(η2,1- C7H7), and (η5-C7H7)2Cr2(CO)4, respectively. The global minima for (C7H7)2Cr2(CO)n (n = 3, 2) have rearranged C7H7 groups. Singlet and triplet structures with heptahapto η7-C7H7 rings are found for the dimetallocenes (η7-C7H7)2Cr2(CO) and (η7-C7H7)2Cr2, with the singlet structures being of much lower energies in both cases. 相似文献
10.
Shoubin Wang Junfeng Li Xugeng Guo Lihui Jiang Jinglai Zhang 《Journal of Molecular Structure》2009,900(1-3):118-120
In this work we report the structures and stabilities of linear carbon clusters HC2nS (n = 1–5) in their ground states using the B3LYP density functional. The rotational constants at the optimized geometries give excellent agreement with the experimental and previous theoretical values. The vertical excitation energies of the 22Π ← X2Π transitions at the CASPT2 level are 3.16, 2.66, 2.05, 1.78, and 1.55 eV, respectively, in good agreement with the corresponding observed values of 3.01, 2.48, 2.10, 1.84, and 1.65 eV. Also, the exponential-decay curves for these vertical excitation energies obtained from experiments and theoretical calculations are illuminated. 相似文献
11.
The structural, energetic and magnetic properties of MnC(M = Fe, Co, Ni, Cu, n = 1–6) clusters are systematically investigated by density-functional calculations. We found that the ground-state geometrical structures of MnC clusters are different from those of pure Mn+1 clusters. Fe4C, Ni2C and Cu4C possess relatively higher stabilities. Doping of a C atom enhances the binding energy of Mn clusters, and the binding energies of Fen-C, Con-C and Nin-C are stronger than that of Cun-C. 相似文献
12.
CnS (1 ≤ n ≤ 20) clusters have been investigated by means of the density functional theory. As a general rule, when 1 ≤ n ≤ 17 the energetically most favorable isomers are found to be the linear arrangement of nuclei (C∞v) with the sulphur atom at the very end of the carbon chain. The electronic ground state is alternately predicted to be 1∑+ for odd n or 3∑− for even n with a conspicuous odd–even effect in the stability of these clusters. The C18S cluster is predicted to have a S-capped monocyclic structure (1A1), but with a low barrier to linearity. On the other hand, C19S and C20S are unambiguously linear in the 1∑+ and 3∑− electronic ground states, respectively. 相似文献
13.
Complexes of ammonia molecules and one chloride ion have been studied by photodetachment and IR-photodissociation spectroscopy. For the smallest anionic complex, the stabilisation energy with respect to the bare chloride ion and vibrational frequencies have been determined. Two bands showed a splitting due to rotational branches, which could be represented by simulation. Rotational constants obtained by former ab initio calculations [P.S. Weiser, D.A. Wild, P.P. Wolynec, E.J. Bieske, J. Phys. Chem. A 104 (2000) 2562] are confirmed and rotational constants of a vibrationally excited state are supplied. IR-photodissociation spectra of clusters with up to four ammonia molecules per chloride ion were recorded. 相似文献
14.
Bao-xing Li Gui-ying Wang Mei-ying Ye Guangcan Yang Chang-hong Yao 《Journal of Molecular Structure》2007,820(1-3):128-140
We have investigated the effect of aluminum impurity atoms on the geometric structures and stabilities of neutral and ionic Sin (n = 2–21) clusters in detail by using full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method. Our calculations suggest that most of the ground state structures for neutral and ionic SinAl (n = 1–20) clusters can be obtained by substituting one Si atom of their corresponding Si clusters with an Al atom. The neutral Sin–1Al clusters with one Al atom have similar geometrical configurations to those of the pure Sin clusters except for local structural distortion. But one Al impurity atom probably reverses the energy ordering of two isomers with small difference. Although, an Al heteroatom reduces the average binding energies for the mixed clusters, it would improve the bond strength between Si atoms in some mixed clusters. Our calculations also suggest that most of the ionic Sin–1Al clusters adopt the same geometrical configurations as their neutral clusters. But for one selected mixed cluster, the charged structures probably have different energy ordering from the neutral clusters. The anionic Sin–1Al− clusters, which are isoelectronic to their corresponding pure Sin clusters, show similar magic behavior. 相似文献
15.
Zhida Chen Yuqing Deng Jiang Bian Lemin Li Guangxian Xu 《Journal of Molecular Structure》1998,434(1-3)
A nonlocal density functional theory (DFT) method has been applied to the calculations on optimized geometry, Mulliken atomic net charges and interatomic Mulliken bond orders as well as total bonding energies (E) in the binary transition metal carbonyl anions with different reduced states [M(CO)n]z− (M=Cr, n=5, 4, 3, z=2, 4, 6; M=Mn, n=5, 4, 3, z=1, 3, 5; M=Fe, n=4, 3, 2, z=2, 4, 6; M=Co, n=4, 3, 2, z=1, 3, 5). For comparison of relative stability, a relative stabilization energy D is defined as D=E([M(CO)n]z−)−nE(CO). The calculated C–O distances are lengthened monotonously with the increase of the anionic charge, but the M–C distances are significantly lengthened only in the higher reduced states. The relative stabilization energy calculated is a considerable negative value in the lower reduced states, but a larger positive value in the higher reduced states. The DFT calculations show that with the increase of the anionic charge, the Mulliken net charges on the M, C, and O atoms all increase, however, an excess of the anionic charge is mainly located at the central metal atom. The calculated C–O Mulliken bond orders decrease consistently with the increase of the anionic charge, but the M–C bond orders exhibit an irregular behavior. However, the total bond orders calculated clearly explain the higher reduced states to be considerably unstable. From analysis of the calculated results, it is deduced that the stability of the binary transition metal carbonyl anions [M(CO)n]z− studied are associated with the coordination number n and the anionic charge z, further, it is possible for the anions studied to be stable if n≥z, conversely, it is impossible when n<z. 相似文献
16.
Guo-dong Tang Zheng-jing Jiang Rong-qing Li Jin-fang Zhang Yu Zhang Chi Zhang 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):228-232
Theoretical calculations were carried out on some neutral nest-shaped heterothiometallic cluster compounds [MOS3Py5Cu3X] (M = Mo, W; X = F, Cl, Br, I) with the high first static hyperpolarizabilities β values. The geometries of these cluster compounds were optimized by the restricted DFT method at B3LYP level with LanL2DZ base set without any constrains. In order to understand the relationship between the first static hyperpolarizabilities and the compositions of these clusters, the frontier orbital compositions and energy gaps between the HOMO and LUMO orbitals were calculated and analysed. In these clusters the HOMO orbitals are mainly composed of halogen atoms and the first static hyperpolarizability increases from F to I atom. The LUMO orbitals of clusters [MoOS3Py5Cu3X] are comprised of Mo, O and S atoms while the LUMO orbitals of clusters [WOS3Py5Cu3X] composed of W atom and pyridine ring. The energy gaps between the HOMO and LUMO orbitals of the clusters [MoOS3Py5Cu3X] are smaller than those of the clusters [WOS3Py5Cu3X]. As a result the first static hyperpolarizability values of the clusters [MoOS3Py5Cu3X] are higher than those of the clusters [WOS3Py5Cu3X]. 相似文献
17.
Electronic spectra of the linear magnesium-containing carbon chains MgC2nH (n = 1–5): A CASPT2 study
Complete active space self-consistent-field (CASSCF) approach has been used for the geometry optimization of the X2Σ+ and A2Π electronic states for the linear magnesium-containing carbon chains MgC2nH (n = 1–5). Multireference second-order perturbation theory (CASPT2) has been used to calculate the vertical excitation energies from the ground to selected seven excited states, as well as the potential energy curves of two 2Σ+ and two 2Π electronic states. The studies indicate that the vertical excitation energies of the A2Π ← X2Σ+ transition for MgC2nH (n = 1–5) are 2.837, 2.793, 2.767, 2.714, and 2.669 eV, respectively, showing remarkable linear size dependence. Compared with the previous TD-DFT and RCCSD(T) results, our estimates for MgC2nH (n = 1–3) are in the best agreement with the available observed data of 2.83, 2.78, and 2.74 eV, respectively. In addition, the dissociation energies in MgC2nH (n = 1–5) are also been evaluated. 相似文献
18.
Uracil–(H2O)n (n = 1–7) clusters were systemically investigated by ab initio methods and the newly constructed ABEEMσπ/MM fluctuating charge model. Water molecules have been gradually placed in an average plane containing uracil. The geometries of 38 uracil–water complexes were obtained using B3LYP/6-311++G** level optimizations, and the energies were determined at the MP2/6-311++G** level with BSSE corrections. The ABEEMσπ/MM potential model gives reasonable properties of these clusters when comparing with the present ab initio data. For interaction energies, the root mean square deviation is 0.96 kcal/mol, and the linear coefficient reaches 0.997. Furthermore, the ABEEMσπ charges changed when H2O interacted with the uracil molecule, especially at the sites where the hydrogen bond form. These results show that the ABEEMσπ/MM model is fine giving the overall characteristic hydration properties of uracil–water systems in good agreement with the high-level ab initio calculations. 相似文献
19.
Vitaly E. Matulis Aliaksei S. Mazheika Oleg A. Ivashkevich 《Journal of Molecular Structure》2008,850(1-3):61-66
Based on both total energy calculations and comparison of experimental and calculated characteristics of photoelectron spectra (PHES), the structural assignment of clusters and has been made using DFT model with recently developed S2LYP functional. The calculated characteristics of PHES for the assigned structures are in excellent agreement with the experimental ones. The electronic structure, geometry and energetic characteristics of low-lying isomers have also been studied. The calculated geometrical parameters of and clusters as well as the geometries of earlier established clusters have been compared with the geometrical characteristics of anionic sodium clusters. The structures of anionic silver and sodium clusters have been found to be very similar. The difference has been observed only for . Based on similarity of the geometries of silver and sodium clusters as well as on the comparison of calculated and experimental characteristics of PHES, the geometry of cluster has been assigned. 相似文献
20.
In this paper, we report the design of models for interstellar molecules HCnN (n = 1–17) by means of the B3LYP density functional method. We performed geometry optimization and calculation on vibrational frequency. We find that the ground-state (G-S) isomers of HCnN (n = 1–17) are with the N atom located at one end and the H atom at the other end of a Cn chain; they are all linear except for HC2N which is bent. When n is odd, the Cn chain is polyacetylene-like whereas when n is even, the Cn chain displays a structure that is cumulenic-like in the middle of the Cn chain. It is found that the G-S isomers of odd-n HCnN (n = 1–17) are more stable than those of even-n ones. The finding is in accord with the relative intensities of HCnN recorded in laboratory investigations, and in consistent with the results of objects observed in interstellar media. We provide explanations for such a trend of even/odd alternation based on concepts of the highest vibrational frequency, bonding character, electronic configuration, incremental binding energy, nucleus-independent chemical shift, and dissociation channels. 相似文献