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1.
二氧化钚分子的多体展式势能函数   总被引:4,自引:0,他引:4  
从导出基态PuO2分子的电子状态X5Σ g正确地判断其离解极限出发,采用MP2方法,应用相对论有效原子实模型(RECP)优化出PuO2(X5Σ g)分子稳定构型为线性OPuO(D∞h),其平衡核间距Re=0.18004nm.同时也计算出振动频率,并优化出存在亚稳态的Pu-O-O(C∞v)构型.使用多体项展式理论方法,导出了基态PuO2分子的分析势能函数.该势能表面准确地再现了O-Pu-O(D∞h)平衡结构和亚稳态的Pu-O-O(C∞v)构型.然后根据势能函数等值图讨论了O(3Pg) PuO反应的势能面静态特征.  相似文献   

2.
C_3O_2分子结构和光谱的密度泛函理论研究   总被引:2,自引:0,他引:2  
使用密度泛函理论,在B3LYP/6-31G(d)和B3LYP/6-311G(2d)水平上,研究了C_3O_2分子的可能几何构型,并在6-31G(d)水平上计算了其中2种总能量最小的构型的振动频率,同时与实验观察值进行了比较, 计算结果当C_3O_2分子具有C2v对称性的W型弯曲结构(键角C-C-C和C-C-O分别为162.3°和178.8°)时,振动频率的计算值和实验观察值非常吻合。  相似文献   

3.
在B3LYP/6-31l++G(3df, 2pd)水平上全优化得到了三甲基铝双聚体(d-TMA)的C2h和C2v两种构型和单体的C3h结构. 着重用完全基组方法CBS-4M模拟计算了TMA气相平衡中各物种在1.01×105 Pa和300~550 K范围内的热力学函数值. 通过考察d-TMA三线态构型和异裂反应对系统熵值的影响, 准确计算了d-TMA离解反应的ΔrHm和ΔrSm. 以lnKd对1/T作图, 两者之间具有很好的线性关系: lnKd=−9624.4363/T+20.2303, 相关系数R2=1.0000, 与前人实验结果相当一致. 在此基础上提出了新的d-TMA气相离解-缔合反应机理.  相似文献   

4.
氯代苯阳离子的密度泛函理论研究   总被引:1,自引:0,他引:1  
采用B3LYP方法及6-311G(d,p)和6-311+G(d,p)基组,对12种氯代苯阳离子进行了理论研究,优化其电子基态的结构,计算了对应分子的垂直电离势(VIP)和绝热电离势(AIP).依据Jahn-Teller理论,确定了1,3,5-C6H3Cl3+和C6Cl6+离子分别具有C2v(2B1)和D2h(2B2g)结构(对应分子分别为D3h和D6h结构).其余10个离子的构型的对称点群与对应分子相同,但构型参数值有明显差别.用B3LYP方法计算的各氯代苯分子的垂直电离势和绝热电离势与实验值符合得很好.  相似文献   

5.
用B3LYP/6-311G(d,p)密度泛函方法对B2H5^ 阳离子和B2H5^.自由基的几何异构体的空间构型进行了优化,并在此基础上用QCISD(T)/6-311++G(3df,2p)偶合簇法进行了单点能计算和零点能校正。结果表明,B2H5^ 单态有2种稳定的几何构型(D3h,C1),其中C1构型是新发现的。B2H5^ 三重态阳离子除已知C,构型外,又发现两种稳定构型(C1),对于B2H5^.自由基体系,共有45中异构体(包括两种新发现的构型Cs),其中,具有单桥结构的C2v最稳定,用二级多体微扰理论和密度泛函方法对前人所认国稳定的B2H5^ 单态的C2v构型进行了全优化,结果发现该构型始终具有一个虚频,不是稳定构型。对B2H5^-阴离子体系的单态和三重态进行的全优化,理论上得出单态时具有C2v和Cs两种稳定构型,而三重态只有C2v一种稳定构型。  相似文献   

6.
利用密度泛函方法对标题化合物的平衡几何、热化学及振动频率进行了理论预测,发现这3种金属原子都有相似的M(CO)n(n=4~7)结构.全局最低构型对M(CO)7都是单态C3v戴帽八面体7S-1,对M(CO)6都是三重态D3d畸变八面体6T(而对应的单重态M(CO)5仅比它低不到21 kJ·mol-1).对M(CO)n(n=5,4)都是三重态6S-1,其构型分别为从6T中移去1个或2个CO基的衍生物5T和4T.此外,五重态的D3h的三角双锥M(CO)5和单态的Td四面体M(CO)4以及能量更高的含有C和O同时与金属成键的独特配位CO基的M(CO)6和M(CO)3也被发现.最后,给出M(CO)7→M(CO)6+CO反应的离解能.并讨论了金属18价电子的Ti(CO)7存在的可能性.  相似文献   

7.
在HF/6-311G(d,p)、 MP2/6-311G(d,p)和B3LYP/6-311G(d,p)水平上,对H2CO和CH3CN以及设计的4种结构H2CO…CH3CN复合物等进行几何全优化和振动频率计算,排除振动频率为负值的非局域极小点结构,并对稳定的环状构型复合物结合能进行基组重叠误差校正和零点振动能校正.分子间相互作用的能量分解分析显示,静电能在H2CO...CH3CN相互作用能量中占主导地位,电荷转移能居第二位.  相似文献   

8.
采用密度泛函理论(DFT)的B3LYP方法和相对论有效原子实势理论模型(RECP),对UC2分子可能的结构进行优化计算,得到UC2分子稳定构型为角形C-U-C(C2v);由微观可逆性原理,判断了UC2分子的离解极限;并且导出了基态UC2分子(X 5B1)的多体项展式势能函数,其势能面等值图展现了C-U-C(C2v)稳定结构;根据势能面等值图,讨论了C+UC(X 3П)反应和U+C2(X 1∑+g)反应的势能面静态特征.  相似文献   

9.
李文佐  黄明宝 《化学学报》2004,62(9):883-887,M004
用B3LYP方法及6-311G(d,p)和6-311 G(d,p)基组,对十二种氟代苯阳离子做了理论研究,优化了它们的电子基态的结构,计算了对应分子的垂直电离势(VIP)和绝热电离势(AIP).依据Jahn.Teller理论,计算确定了1,3,5-C6H3F^ 3和C6F^ 6离子分别具有C2v(2↑B)和D2h(2↑B2g)结构(对应分子分别为D3h和D6h结构).其余十个离子的构型的对称点群与对应分子相同,但构型参数值有明显差别.自然布居分析计算表明这些离子的正电荷主要分布在与F原子相连的C原子和各H原子上.B3LYP/6-311 G(d,p)级别上计算的各氟代苯分子的VIP和AIP值和实验值符合得很好.  相似文献   

10.
黄多辉  王藩侯  朱正和 《化学学报》2008,66(16):1915-1918
以6-311++G(d)为基函数, 采用CASSCF方法优化出Li2O+分子的稳定构型为线形Li-O-Li (C∞V), 电子组态为2∏, 并对平衡核间距、离解能和基态简正频率进行了计算. 根据原子分子反应静力学原理, 导出了Li2O+分子的合理的离解极限. 并运用多体展式理论方法首次导出了基态Li2O+分子的分析势能函数, 绘出了势能等值图, 其势能等值图准确地再现了Li2O+分子的平衡结构特征.  相似文献   

11.
Total integral cross sections for 4He + H2 (ν = 0, j = 0) → 4He + H2 (ν′ = 1, j′ = 0, 2) have been calculated in the total energy range 1.2 to 5.5 eV, according to a quantal sudden approximation for the H2 rotational degrees of freedom and a close coupling expansion of the vibrational degree of freedom. Convergence of the above cross sections is investigated by employing four vibration basis sets in the close coupling calculations, i.e., ν = 0,1, ν = 0,1, 2, ν = 0, 1, 2, 3 and ν = 0, 1, 2, 3, 4. Between 4.2 and 5.5 eV calculations were done with three vibration basis sets; ν = 0.–4, ν = 0–5, and ν = 0–6. It is found that at least four vibrational basis functions are needed to converge (to within 5–10%) these cross sections in the above energy range. Comparison of breathing sphere calculations and summed sudden rotation results shows good agreement for the (weakly anisotropic) Mies-Krauss potential. However, as expected the former results underestimate the vibrational 0 → 1 total integral cross sections.  相似文献   

12.
Spectroscopie Investigations on R? C6H4O(CH3)2SiF Compounds The i.r. and Raman spectra of a number of R? C6H4O(CH3)2SiF compounds (R = H, CH3, CH3O, Cl, Br, NO2, NH2) have been recorded. The intramolecular and intermolecular interactions were discussed by means of ν SiF, ν Si? O? (C), ν C? O? (Si) and νs SiC2 vibrations.  相似文献   

13.
A quasiclassical trajectory study has been carried out to investigate the dynamics of collisions between H + H2(1 ? ν ? 4) and D + D2(1 ? ν ? 4), using the accurate Yates-Lester potential. Reaction is selectively enhanced by the vibrational excitation of the diatomic reagent, as judged by information theory, but the degree of selectivity falls as the vibrational energy is successively increased. The calculated results are in fair agreement with experimental measurements on the removal of H2(ν = 1) by H but not with those for D2(ν = 1) by D.  相似文献   

14.
Infrared (4000-400 cm(-1)) and Raman (3500-50 cm(-1)) spectral measurements have been made for the solid sample of 7-methyl-4-bromomethylcoumarin. Electronic structure calculations at RHF/6-31G* and B3LYP/6-31G* levels of theory have been performed, giving equilibrium geometries, harmonic vibrational spectra and normal modes. Different orientations of bromomethyl group have yielded only two conformers, of which the most stable one lying lower from the other conformer by approximately 7.99 kJ/mol, is non-planar with no symmetry. A complete assignment of the vibrational modes, aided by the calculations, has been proposed. Coupled vibrations are manifest in many modes. Some spectral features, compared to 6-methyl-4-bromomethylcoumarin, show changes across both IR and Raman spectra, involving mainly skeletal vibrations, and to a lesser degree, methyl and bromomethyl vibrations. Low-frequency vibrations below 150 cm(-1) are assigned to lattice modes.  相似文献   

15.
By preparing ethylene [C2H4(X1Ag)] in selected rotational levels of the nu11(b1u), nu2+nu12(b1u), or nu9(b2u) vibrational state with infrared (IR) laser photoexcitation prior to vacuum ultraviolet (VUV) laser photoionization, we have recorded rotationally resolved pulsed field ionization-photoelectron (PFI-PE) spectra for C2H4+(X2B3u) in the energy region of 0-3000 cm(-1) above the ionization energy (IE) of C2H4(X1Ag). Here, nu2(ag), nu9(b2u), nu11(b1u), and nu12(b1u) represent the C-C stretching, CH2 stretching, CH2 stretching, and CH2 bending modes of C2H4(X1Ag), respectively. The fully rovibrationally resolved spectra have allowed unambiguous symmetry assignments of the observed vibrational bands, which in turn have provided valuable information on the photoionization dynamics of C2H4. The IR-VUV photoionization of C2H4(X1Ag) via the nu11(b1u) or nu2+nu12(b1u) vibrational states is found to predominantly produce vibrational states of C2H4+(X2B3u) with b1u symmetry, which cannot be observed in single-photon VUV-PFI-PE measurements of C2H4(X1Ag). The analysis of the observed IR-VUV-PFI-PE bands has provided the IE(C2H4) = 84,790.2(2) cm(-1) and accurate vibrational frequencies for the nu4+(au)[84.1(2) cm(-1)], nu12+(b1u)[1411.7(2) cm(-1)], nu4+ +nu12+(b1g)[1482.5(2) cm(-1)], nu2+(ag)[1488.3(2) cm(-1)], nu2+ + nu4+(au)[1559.2(2) cm(-1)], 2nu4+ + nu12 +(b1u)[1848.5(2) cm(-1)], 4nu4+ + nu12 +(b1u)[2558.8(2) cm(-1)], nu2+ + nu12 +(b1u)[2872.7(2) cm(-1)], and nu11+(b1u)[2978.7(2) cm(-1)] vibrational states of C2H4+(X2B3u), where nu4+ is the ion torsional state. The IE(C2H4) and the nu4+(au), nu2+(ag), and nu2+ + nu4+ (au) frequencies are in excellent accord with those obtained in previous single-photon VUV-PFI-PE measurements. The other ion vibrational frequencies represent new experimental determinations. We have also performed high-level ab initio anharmonic vibrational frequency calculations for C2H4(X1Ag) and C2H4+(X2B3u) at the CCSD(T)/aug-cc-pVQZ level for guidance in the assignment of the IR-VUV-PFI-PE spectra. All theoretical vibrational frequencies for the neutral and ion, except the ion torsional frequency, are found to agree with experimental vibrational frequencies to better than 1%.  相似文献   

16.
The Raman spectrum of crystalline dodecahedrane, C20H20, a species of nominal I(h) symmetry, exhibits splitting of the H(g) Raman active modes. The Raman inactive gerade vibrations of G(g), T(1g), and T(2g) symmetry are found to have weak Raman activity. The IR forbidden vibrations of T(2u), G(u), and H(u) type have moderate IR activity. All of this is consistent with the T(h) site symmetry. A treatment of the structure and vibrations of dodecahedrane using a periodic lattice DFT method results in a slightly distorted T(h) structure with six C-C bonds that are 0.001 A longer than the other 24. The vibrational spectrum computed for this structure exhibits splittings of the H(g) modes that are consistent with the observed spectra, but the computed splittings are larger than observed in room-temperature data. A complex pattern observed in the C-H stretching region is assigned. The inelastic neutron scattering spectrum calculated from the computed normal modes for the T(h) molecule in the lattice agrees quantitatively with experiment when overtone and combination transitions are included and allowance is made for anharmonicity of the C-H stretch motion. Finally, it is argued that the existing crystallographic determination of the average C-C bond length of 1.544 A is shortened by disorder and should be revised upward to agree with the computed value of 1.558 A.  相似文献   

17.
C60分子间相互作用的Morse势函数及应用   总被引:1,自引:0,他引:1  
刘奉岭 《物理化学学报》2002,18(11):967-972
利用C60晶体的升华焓、晶胞参数等性质,得到C60分子间相互作用的Morse势函数,其解析表达式为 u(r)=30.05 exp[-24.96(r-1.005)]-60.10 exp[-12.48(r-1.005)] 采用该作用势研究了C60及其晶体的一些性质, 如计算得到C60晶体(100)面的表面能为7.46×10-2 J•m-2, 在650~4500 K温度范围内计算了C60分子的第二维里系数, 研究了C60面心立方晶体的晶格振动, 并计算得到了晶格振动的态密度分布,还利用该作用势研究了不同晶型时C60晶体的稳定性.  相似文献   

18.
Spectra emitted from 0.1% CO-N2 solids excited with high energy electrons at 4 K show evidence for resonant transfer of vibrational energy from highly excited vibrational levels of N2 to CO in the process N2(X1Σg+, ν) + CO(ν = 0) → N2(X1Σg+, ν - 1) + CO(ν = 1) + phonons. Energy transfer from levels with ν ? 9 has been observed.  相似文献   

19.
The FT-IR and FT-Raman spectra of 2-bromo-4-chlorotoluene (2B4CT) molecule have been recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Optimized geometrical structures, harmonic vibrational frequencies, intensities, reduced mass, force constants and depolarization ratio have been computed by the B3 based (B3LYP) density functional methods using 6-31+G(d,p) and 6-311++G(d,p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies are analysed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The Mulliken charges, the natural bonding orbital (NBO) analysis, the values of electric dipole moment (μ) and the first-order hyperpolarizability (β) of the investigated molecule were computed using DFT calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The influences of bromine atom, chlorine atom and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed.  相似文献   

20.
A liquid-nitrogen-cooled, active-N2-pumped CO laser has produced cw oscillation from ν = 2 → ν = 1 (4.8 μm) to ν = 35 → ν = 34 (8.0 μm). An analysis of the output spectrum gives the VT relaxation rate of CO (ν ≈30) by He at 150°K as 2 × 103 sec−1 torr−1.  相似文献   

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