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采用密度泛涵理论(density functional theory, DFT)中的广义梯度近似(generally gradient approximation, GGA)对富勒烯C72和内掺金属La富勒烯La2@C72三种同分异构体的几何结构和电子结构进行研究.发现在C72的三种同分异构体中,满足独立五边形规则(isolated-pentagon-rule,IPR)的C72(D6d<
关键词:
72')" href="#">C72
2@C72')" href="#">La2@C72
密度泛涵理论
几何结构
电子结构 相似文献
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Ding Changgeng Yang Jinlong Cui Xiangyuan Wang Kelin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):123-126
Geometrical and electronic structures of C35X fullerenes with , N and Si as substitutional dopants have been studied. Three non-equivalent sites in the D6h structure of C36 have been considered for the substitution. We have found that the dopant has a strong tendency to substitute at sites where
the carbon atom contributes significantly to the frontier orbitals of C36 and has the weakest interaction with its nearest-neighbor atoms. The relative stability of C35Si and C35B (C35N) has been investigated and high chemical reactivity of C35Si has been predicted.
Received 8 July 1999 and Received in final form 4 October 1999 相似文献
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Keinosuke Hamada 《光谱学快报》2013,46(6-7):537-543
There are two possible configurations for H2O, linear(D∞h) or bent(C2v). For a C2v′, the three bands ν1′ ν2 and ν3 should appear in both Raman and infrared. For a D∞h. however, the ν1, band should appear in only Raman and the ν2 and ν3 bands, in only infrared, that is, a principle of mutual exclusion of Raman and infrared should hold. The present author concludes that H2X and D2X(X=O, S, Se, Te) have a linear D∞h. structure, since the obtained spectra show mutual exclusion of Raman and infrared. 相似文献
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The density functional theory (DFT) method (b3p86) of Gaussian 03 is used to optimize the structure of the Ni2 molecule. The result shows that the ground state for the Ni2 molecule is a 5-multiple state, symbolizing a spin polarization effect existing in the Ni2 molecule, a transition metal molecule, but no spin pollution is found because the wavefunction of the ground state does not mingle with wavefunctions of higher-energy states. So the ground state for Ni2 molecule, which is a 5-multiple state, is indicative of spin polarization effect of the Ni2 molecule, that is, there exist 4 parallel spin electrons in Ni2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Ni2 molecule is minimized. It can be concluded that the effect of parallel spin in the Ni2 molecule is larger than that of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters of the ground state and other states of the Ni2 molecule are derived. The dissociation energy De for the ground state of the Ni2 molecule is 1.835 eV, equilibrium bond length Re is 0.2243 nm, vibration frequency we is 262.35 cm^-1. Its force constants f2, f3 and f4 are 1.1901 aJ.nm^-2, -5.8723 aJ.nm^-3, and 21.2505 aJ.nm^-4 respectively. The other spectroscopic data for the ground state of the Ni2 molecule ωeχe, Be and αe are 1.6315cm 2, 0.1141 cm^-1, and 8.0145× 10^-4 cm^-1 respectively. 相似文献
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The density functional theory method (DFT) (b3p86) of Gaussian 03 has been used to optimize the structure of the Mn2 molecule. The result shows that the ground state of the Mn2 molecule is an 11-multiple state, indicating a spin polarization effect in the Mn2 molecule, a transition metal element molecule. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions of higher-energy states. So the ground state for Mn2 molecule being of an 11-multiple state is the indicative of spin polarization effect of the Mn2 molecule among those in the transition metal elements: that is, there are 10 parallel spin electrons in a Mn2 molecule. The number of non-conjugated electrons is the greatest. These electrons occupy different spacious orbitals so that the energy of the Mn2 molecule is minimized. It can be concluded that the effect of parallel spin in the Mn2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state and other states of the Mn2 molecule are derived. The dissociation energy De for the ground state of the Mn2 molecule is 1.4477 eV, equilibrium bond length Re is 0.2506 nm, vibration frequency ωe is 211.51 cm^-1. Its force constants f2, f3, and f4 are 0.7240 aJ·nm-2, -3.35574 aJ·nm^-3, 11.4813 aJ·nm^-4 respectively. The other spectroscopic data for the ground state of the Mn2 molecule ωeχe, Be, αe are 1.5301 cm^-1, 0.0978 cm^-1, 7.7825×10^-4 cm^-1 respectively. 相似文献
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Elastic, strength, electronic properties and vibrational spectra of Ne@C60 (I h) in its ground electronic state (X 1Ag) were investigated with density functional theory at B3PW91/6-31G level via structure distortions. The elastic properties were obtained from the potential energy curves (PECs) in all of the five independent distortional directions of the molecule with symmetries of 1. D 5d, 2. D 3d, 3. D 2h, 4. C 2h(1) and 5. C 2h(2). PECs were examined where the structure of Ne@C60 was destroyed. The necessary energies to destroy the structure were thus obtained, which illuminated the stability of Ne@C60. PECs were found to be anisotropic and were accurately fitted to polynomials. Elongations in the direction of D 5d and compression in D 2h encountered potential energy surface cross-linkages, which might be considered as a single electron pump for further application in the design of single electron devices. Time-dependent B3PW91/6-31G analysis predicted significant electronic spectra changes associated with structure distortions. Similarities and differences of the properties were compared with those in C60 and He@C60. 相似文献
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The equilibrium structures and the electronic, spectroscopic and thermodynamic properties of small Pun (n=2-5) molecules are systematically investigated using the methods of general gradient approximation (GGA) of density functional theory (DFT). The results show that the bond length of the lowest-energy structure of Pu2 is 2.578 AA. The ground state structure of Pu3 is a triangle with D3h symmetry, whereas for Pu4, the ground state structure is a square (D4h) and the spin polarization of 16 for molecule Pu5 with square geometry (D4h) is the most stable structure. For the ground state structures, the vibrational spectra as well as thermodynamic parameters are worked out. In addition, the values for the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) along with the energy gap of all the Pu2-5 structures are presented. The relevant structural and chemical stabilities are predicted. 相似文献
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室温下在单晶Si中注入(0.6—1.5)at%的C原子,部分样品在C离子注入之前在其中注入29Si+离子产生损伤,然后在相同条件下利用高温退火固相外延了Si1-xCx合金,研究了预注入对Si1-xCx合金形成的影响.如果注入C离子的剂量小于引起Si非晶化的剂量,在950℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇,难于形成Si1-xC关键词:
离子注入
固相外延
1-xCx合金')" href="#">Si1-xCx合金 相似文献
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A tensorial formalism adapted to the case of the X2Y4 molecules with D2h symmetry has been developed in the same way as in the previous works on XY4 (Td) and XY6 (Oh) spherical tops and XY5Z (C4v) symmetric tops. Here, we use the O(3)⊃D2h group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain and used in the case of the Hamiltonian and transition moment operators. 相似文献
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运用Gaussian03软件包,采用密度泛函理论中的B3P86 方法,结合6-311++G**(3df,3pd) 基组对基态SiF2分子的平衡电子结构和谐振频率进行了优化计算,得到了其稳定结构为C2v构型.SiF2基态电子态为X1A1,平衡核间距RSi—F=0.1061 nm,键角αF—Si—F=100.6762°,离解能De=13.8 eV.应用多体项展式理论推导了基态SiF2分子的解析势能函数,其等值势能图准确地再现了SiF2分子的平衡构型特征和能量变化.
关键词:
2')" href="#">SiF2
Murrell-Sorbie函数
多体项展式理论 相似文献
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The transport properties of the six-atom carbon ring cluster C6 sandwiched between Al(100) electrodes have been investigated by first-principles nonequilibrium Green's function technique. Our results demonstrate that the transport properties of monocyclic C6 with D3h symmetry, with alternating bond angles, the most stable C6 isomer, show metallic conductance. The charge transfer between the central molecule and the electrodes is very important for its transport properties. We also compare the equilibrium transmission spectra for C6 in different isomers. 相似文献
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采用Gaussian 98程序,运用B3LYP方法,对Pd和Pb原子采用收缩价基组LANL2DZ,对Pb2和PdPb2分子的微观结构进行了理论计算. 由于Pb2分子离解后一个Pb原子处于基态,另一个Pb原子处于激发态,采用最小二乘法拟合Pb2分子的势能函数,选用的函数形式为Murrell-Sorbie势能函数加上开关函数. 使用多体展式理论导出了势函数中的参数进而给出PdPb2分子基态势函数的解析表达式,其势能面准确地复现了PdPb2分子的两个稳定构型(C2V和C∞v)及其能量关系.
关键词:
2')" href="#">Pb2
2')" href="#">PdPb2
势能函数 相似文献
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运用二次组态相关(QCISD)方法,分别选用6-311++G(3df,3pd)和D95(3df,3pd)基组,对BH2和AlH2分子的结构进行了优化计算,得到BH2分子的稳态结构为C2v构型,电子态为2A1、平衡核间距RBH=0.1187nm、键角∠HBH=128.791°、离解能De=3.65eV、基态振动频率ν1(a1)=1020.103cm-1,ν2(a1)=2598.144cm-1,ν3(b2)=2759.304cm-1.AlH2分子的稳态结构也为C2v构型,电子态为2A1、平衡核间距RAlH=0.1592nm、键角∠HAlH=118.095°、离解能De=2.27eV、基态振动频率ν1(a1)=780.81cm-1,ν2(a1)=1880.81cm-1,ν3(b2)=1910.46cm-1.采用多体项展式理论推导了基态BH2和AlH2分子的解析势能函数,其等值势能图准确再现了BH2和AlH2分子的结构特征及其势阱深度与位置.分析讨论势能面的静态特征时得到BH+H→BH2反应中存在鞍点,活化能为150.204kJ/mol;AlH+H→AlH2反应中也存在鞍点,活化能为54.8064kJ/mol.
关键词:
2')" href="#">BH2
2')" href="#">AlH2
Murrell-Sorbie函数
多体项展式理论
解析势能函数 相似文献
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The geometries, stabilities and electronic structures of Al n Cu m (n?=?5–9, m?=?1–3) clusters were explored by using the genetic algorithm combined with ab initio methods. The geometric structures are almost spherical when the valence electrons are around the magic number 20, otherwise the structures are oblate or prolate. The stabilities of the clusters are related to both the Cu/Al ratios and the electronic configurations. The clusters with lower Cu/Al ratios have high stabilities. The molecular orbitals are in accord with the shell structures predicted by the jellium model. The 3d orbitals of the Cu atoms are localised, although their orbital energies are between the 1P and 1D jellium orbitals. The Al6Cu2 with 20 valence electrons forms closed 1S21P61D102S2 shells, and shows large binding energy and removal energy, large ionisation potential and small electron affinity. For the no-magic clusters, the structure deformation leads to crystal-field-like splitting of the degenerate shells and stabilises the clusters. 相似文献