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1.
The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometries of c^3∑g^+ and B^1-Пu states of dimer 7Li2 is made at numerous basis sets by using a symmetryadapted-cluster configuration-interaztion (SAC-CI) method in the Gaussian 03 program package. In this paper the difference of the equilibrium geometries obtained by SPES and by OPT is reported. The results obtained by SPES are found to be more reasonable than those obtained by OPT in full active space at the present SAC-CI level of theory. And the conclusion is attained that the cc-PVTZ is a most suitable basis set for these states. The calculated dissociation energies and equilibrium geometries are 0.8818 eV and 0.3090 nm for c^3∑g^+ state, and 0.3668 eV and 0.2932 nm for B^1-Пu state respectively. The potential energy curves are calculated over a wide internuclear distance range from about 2.5α0 to 37α0 and have a least-squares fit into the Murrell-Sorbie function. According to the calculated analytic potential energy functions, the harmonic frequencies (We) and other spectroscopic data (ωeXe, Be and αe) are calculated. Comparison of the theoretical determinations at present work with the experiments and other theories clearly shows that the present work is the most complete effort and thus represents an improvement over previous theoretical results.  相似文献   

2.
Optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy was employed to observe the visible absorption spectra of the B^2∑u^ -X^2∑g^ electronic transition of C2^-. Four hot bands (0,1), (1,2), (2,3) and (3,4) have been observed and the band (3,4) is measured directly for the first time, so far as we know, by absorption. A rotational analysis was carried out to obtain molecular constants. With the Franck-Condon principle and the vibrational Boltzmann distribution, we have estimated the vibrational temperature of C2^- to be about 3000K.  相似文献   

3.
余本海  戴启润  施德恒  刘玉芳 《中国物理》2007,16(10):2962-2967
The density functional theory (B3LYP, B3P86) and the quadratic configuration-interaction method including single and double substitutions (QCISD(T), QCISD) presented in Gaussian03 program package are employed to calculate the equilibrium internuclear distance $R_{\rm e}$, the dissociation energy $D_{\rm e }$ and the harmonic frequency $\omega _{\rm e}$ for the $X{}^{1}\Sigma^{ + }_{\rm g}$ state of sodium dimer in a number of basis sets. The conclusion is gained that the best $R_{\rm e}$, $D_{\rm e}$ and $\omega _{\rm e}$ results can be attained at the QCISD/6-311G(3df,3pd) level of theory. The potential energy curve at this level of theory for this state is obtained over a wide internuclear separation range from 0.16 to 2.0~nm and is fitted to the analytic Murrell--Sorbie function. The spectroscopic parameters $D_{\rm e}$, $D_{0}$, $R_{\rm e}$, $\omega _{\rm e}$, $\omega _{\rm e}\chi _{\rm e}$, $\alpha _{\rm e}$ and $B_{\rm e}$ are calculated to be 0.7219~eV, 0.7135~eV, 0.31813~nm, 151.63~cm$^{ - 1}$, 0.7288~cm$^{ - 1}$, 0.000729~cm$^{ - 1}$ and 0.1449~cm$^{ - 1}$, respectively, which are in good agreement with the measurements. With the potential obtained at the QCISD/6-311G(3df,3pd) level of theory, a total of 63 vibrational states is found when $J=0$ by solving the radial Schr\"{o}dinger equation of nuclear motion. The vibrational level, corresponding classical turning point and inertial rotation constant are computed for each vibrational state. The centrifugal distortion constants ($D_{\upsilon }\, H_{\upsilon }$, $L_{\upsilon }$, $M_{\upsilon }$, $N_{\upsilon }$ and $O_{\upsilon })$ are reported for the first time for the first 31 vibrational states when $J=0$.  相似文献   

4.
刘玉芳  贾毅 《中国物理 B》2011,20(3):33106-033106
This paper calculates the equilibrium internuclear separations, the harmonic frequencies and the potential energy curves of the X^2∑+, A^2П and B^2∑+ states of the CP radical by the highly accurate valence internally contracted multireference configuration interaction method with correlation-consistent basis sets (aug-cc-pV6Z for C atom and aug-cc-pVQZ for P atom). The potential energy curves are all fitted with the analytic potential energy function by the least-square fitting. Employing the analytic potential energy function, we determine the spectroscopic constants (Be, αe and ωeχe) of these states. For the X2∑+ state, the obtained values of De, Be, αe, ωeχe, Re and ωe are 5.4831 eV, 0.792119 cm-1, 0.005521 cm-1, 6.89653 cm-1, 0.15683 nm, 12535.11 cm-1, respectively. For the A2H state, the present values of De, Be,αe, ωeχe, Re and We are 4.586 eV, 0.703333 cm-1, 0.005458 cm-1, 6.03398 cm-1, 0.16613 nm, 1057.89 cm-1, respectively. For the B2E+ state, the present values of De, Be, αe, ωeχe, Re and We are 3.506 eV, 0.677561 cm-1, 0.00603298 cm-1, 5.68809 cm-1, 0.1696 nm, 822.554 cm-1, respectively. For these states, the vibrational states with the rotational quantum number J equals zero (J = 0) are studied by solving the radial nuclear Schr6dinger equation using the Numerov method. For each vibrational state, the vibrational level, the classical turning points, the rotational inertial and the centrifugal distortion constants are calculated. Comparison is made with recent theoretical and experimental results.  相似文献   

5.
研究了CS2分子^1B2(^1∑u^+)预离解态线形势垒下的g振动能级光解动力学,包括预解离寿命、产物振转布居、平动-振动-转动能量分配和解离通道分支比.在实验过程中,一束可调谐激光激发超声射流冷却的CS2分子到^1B2(^1∑u^+)电子态,光解产物CS用另一束可调谐激光通过激光诱导荧光(LIF)方法检测.通过拟合光解碎片激发谱的谱峰轮廓,获得了源于不同跃迁初始态的^1B2(^1∑u^+)态g振动能级的预解离寿命.通过分析CS的LIF光谱,则获得了不同光解波长下CS碎片的v=0—8振动态布居、v=1、4—8振动态的转动布居、能量分配以及两个预解离通道CS(X^1∑^+)+S(^3PJ)和CS(X^1∑^+)+S(^1D2)的分支比.实验还考察了初始态弯曲振动量子数v2″、振动角动量量子数l对解离动力学的影响.发现v2″的影响不大,而l的影响却是明显的.较大的l(=K)对应于较短的寿命和较小的通道分支比S(^3PJ)/S(^1D2),即大的l(=K)有利于预解离的发生,同时更有利于产生S(^1D2).  相似文献   

6.
In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe (klockmannite) using density functional theory. The studies in this work show that the best structural results, in comparison to the experimental values, belong to the PBEsol-GGA and WC-GGA functionals. However, the best results for the bulk modulus and density of states (DOSs) are related to the local density approximation (LDA) functional. Through utilized approaches, the LDA is chosen to investigate the electronic structure. The results of the electronic properties and geometric optimization of α-CuSe respectively show that this compound is conductive and non-magnetic. The curvatures of the energy bands crossing the Fermi level explicitly reveal that major charge carriers in CuSe are holes, whose density is estimated to be 0.86×1022 hole/cm3. In particular, the Fermi surfaces in the first Brillouin zone demonstrate interplane conductivity between (001) planes. Moreover, the charge carriers among them are electrons and holes simultaneously. The conductivity in CuSe is mainly due to the hybridization between the d orbitals of Cu atoms and the p orbitals of Se atoms. The former orbitals have the dual nature of localization and itinerancy.  相似文献   

7.
Three kinds of Er^3+-doped tellurite glasses with different hydroxyl groups are prepared by the conventional melt-quenching method. Infrared spectra are measured to estimate the exact content of OH^- groups in samples. The maximum phonon energy in glasses are obtained by measuring the Raman scattering spectra. The strength parameters Ωt (t = 2, 4, 6) for all the samples are calculated and compared. The nonradiative decay rate of the Er^3+ ^4I13/2 → ^4I15/2 transition are calculated for the glass samples with different phonon energy and OH^- group contents. Finally, the effect of OH^- groups on fluorescence decay rate of Er^3+ is analysed, the constant KOH-Er of TWN, TZPL and TZL glasses are calculated to be 9.2 × 10^-19 cm^4s^-1, 5.9 × 10^-19 cm^4s^-1, and 3.5 × 10^-19 cm^4s^-1, respectively.  相似文献   

8.
The accurate dissociation energy and equilibrium geometry of the 63Π state of 7LiH molecule is calculated using a symmetry-adapted-cluster configuration-interaction method in full active space. And the calculated results are 0.2580 eV and 0.1958 nm for the dissociation energy and equilibrium geometry, respectively. The whole potential energy curve for the 63Π state is also calculated over the internuclear separation range from about 0.10 to 0.54 nm. The results are fitted by the Murrell-Sorbie function. It is found that the Murrell-Sorbie function form, which is mainly used to fit the ground-state potential energy function, is well suitable for the excited triplet b3Π state. The vertical excitation energy from the ground state to the 63Π state is calculated to be 4.233 eV. Based on the analytic potential energy function, the harmonic frequency of 610.88 cm-1 about this state is firstly estimated. Compared with other theoretical results, this work is the most complete effort to deal with the analytic potential energy function and the harmonic frequency of this state.  相似文献   

9.
Using the quasi-classical trajectory method, the product rotational polarization of the ion-molecule reaction He^+D2^+ has been calculated at different collision energies on the PALMIERI potential energy surface [Palmieri et al. Mol. Phys. 98 (2000) 1835]. The distribution angle between k and j′, P(Or), the distribution of the dihedral angle P(Фr), and the angular distribution of product rotational vectors in the form of polar plots in θr and Фr are calculated. In addition, four polarization-dependent differential cross sections are also presented in the center-of-mass frame, respectively. The results indicate that the rotational polarization of the product HeD^+ presents different characters for different collision energies. These discrepancies may be ascribed to the different collision energies and constructions of the potential energy surface.  相似文献   

10.
A quasiclassical trajectory study with the sixth-order explicit symplectic algorithm for the N(^4S)+O2(X^3∑g^-) → NO(X^2Ⅱ) +O(^3P) reaction has been reported by employing a new ground potential energy surface. We have discussed the influence of the relative translational energy, the vibrational and rotational levels of O2 molecules on the total reaction cross section. Thermal rate constants at temperatures 300, 600, and 1000 K determined in this work for the reaction are 4.4 × 10^7, 1.8 × 10^10, and 3.1 × 10^11 cm^3mol^-1s^-1, respectively. It is found that they are in better agreement with the experimental data than previous theoretical values.  相似文献   

11.
We have studied the effects of the finite range of the interaction between the fragments of the projectile on the fusion and/or breakup of 6He+238U and 11Li+208Pb systems at near barrier energies within the framework of dynamic polarization potential approach. It has been found that at near barrier energies the maximum flux is lost to the breakup channel and at energies well above the Coulomb barrier the fusion coupled with the breakup channel opens up, initially with sharp rise and later becoming saturated at energy nearly twice of theCoulomb barrier. Further, it is found that the breakup cross section increases with the increasing range of the interaction between the fragments of the projectile while the fusion coupled with the breakup channel cross section decreases with the increasing range.  相似文献   

12.
Low-energy scattering of D ^*+ and D1^0 meson is studied using quenched lattice QCD with improved lattice actions on anisotropic lattices.The threshold scattering parameters,namely the scattering length a 0 and the effective range r 0,for the s-wave scattering in J P = 0 - channel are extracted: a 0 = 2.52(47) fm and r 0 = 0.7(1) fm.It is argued that,albeit the interaction between the two charmed mesons being attractive,it is unlikely that they can form a shallow bound state in this channel.Our calculation provides some useful information on the nature of the newly discovered resonance-like structure Z + (4430) by the Belle Collaboration.  相似文献   

13.
The reasonable dissociation limit for the G^1Ⅱg, state of dimer ^7Li2 is determined. The equilibrium internuclear distance, dissociation energy, harmonic frequency, vibrational zero energy, and adiabatic excitation energy are calculated using a symmetry-adapted-cluster configuration-interactlon method in complete active space in Gaussian03 program package at such numerous basis sets as 6-311 ++G, 6-311 ++G(2df,2pd), 6-311 ++G(2df, p), cc-PVTZ, 6- 311++G(3df,3pd), CEP-121G, 6-311++G(2df, pd), 6-311++G(d,p),6-311G(3df,3pd), D95(3df,3pd), 6-311++G(3df,2p), 6-311++G(2df), 6-311++G(df, pd) D95V++, and DGDZVP. The complete potential energy curves are obtained at these sets over a wide internuclear distance range and have least squares fitted to Murrell-Sorbie function. The conclnsion shows that the basis set 6-311++G(2df, p) is a most suitable one for the G^1Ⅱg state. At this basis set, the calculated spectroscopic constants Te, De, Eo, Re, ωe, ωeXe, ae, and Be are of 3.9523 eV, 0.813 06 eV, 113.56 cm^-1, 0.320 15 nm, 227.96 cm^-1, 1.6928 cm^-1, 0.004 436 cm^-1, and 0.4689 cm^-1, respectively, which are in good agreement with measurements whenever available. The total 50 vibrational levels and corresponding inertial rotation constants are for the first time calculated and compared with available RKR data. And good agreement with measurements is obtained.  相似文献   

14.
The accurate dissociation energy and harmonic frequency for the highly excited 2^1Пu state of dimer ^7Li2 have been calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space. The calculated results are in excellent agreement with experimental measurements. The potential energy curves at numerous basis sets for this state are obtained over a wide internuclear separation range from about 2.4a0 to 37.0a0. And the conclusion is gained that the basis set 6-311++G(d,p) is a most suitable one. The calculated spectroscopic constants De, Re, ωe, ωeχe, ae and Be at 6-311++G(d,p) are 0.9670 eV, 0.3125 nm, 238.6 cm^-1, 1.3705 cm^-1, 0.0039 cm^-1 and 0.4921 cm^-1, respectively. The vibrational levels are calculated by solving the radial SchrSdinger equation of nuclear motion. A total of 53 vibrational levels are found and reported for the first time. The classical turning points have been computed. Comparing with the measurements, in which only the first nine vibrational levels have been obtained so far, the present calculations are very encouraging. A careful comparison of the present results of the parameters De and We with those obtained from previous theories clearly shows that the present calculations are much closer to the measurements than previous theoretical results, thus representing an improvement on the accuracy of the ab initio calculations of the potentials for this state.  相似文献   

15.
16.
The potential energy curves (PECs) of BO molecule, including ∑^+and ∏ symmetries with doublet spin multiplicities, are obtained employing multi-reference configuration interaction (MRCI) method and Dunning's correlation consistent basis sets. The analytical potential energy functions (APEFs) are fitted using the Murrell-Sorbie (MS) function and the least square method. Based on the PECs, the spectroscopic constants of the states have been determined and compared with the theoretical and experimental results available to affirm the accuracy and liability of the calculations. The root-mean-square (RMS) errors between the fitted results and the ab initio values are too little in comparison with the chemical accuracy (349.755 cm^-1). It is shown that the present APEFs are accurate and can display the interaction between the atoms well. The present APEFs can be used to construct more complicated APEF or do some dynamic investigations.  相似文献   

17.
The α+20Ne elastic scattering angular distributions at lower incident energies of Eα= 12.7--31.1 MeV have been analyzed by using the α-folding potential based on the α+16O structure model of the 20Ne nucleus. The α-folding potential with a standard Woods-Saxon type imaginary part, can reasonably describe experimental cross sections and the anomalous large angle scattering (ALAS) features. The anomaly of the α+20Ne scattering system is further confirmed in the lower incident energy region.  相似文献   

18.
19.
The optical properties of poly(Phenylenevinylene)(PPV)/TiO2 nanocomposites,prepared via the sol-gel process,were investigated by UV-VIS,FT-IR,FL spectroscopy and TEM.TEM images indicated that the surfaces of TiO2 nanoparticles became rough,and finally formed the connected network as the TiO2 content increased.FT-IR spectra showed the titanium butoxide hydrolyzed to from Ti organic compound,which can result in the connected network of TiO2 nanoarticles.The conjugation of PPV polymer chains can be interrupted by the TiO2 network structure,as evdenced in UV-VIS spectra.The investigation of the PL spectra revealed that the emitted light of the PPV/TiO2 nanocoposites blue shifted wihout fine structure,and the PL intensity enhanced,when the TiO2 net work fromed.These phenomena suggested that the optical properties of the PPV/TiO2 nanocomposites were dependent on the interfacial structure between PPV and TiO2 nanoparticles.2001 Elsevier Science B.V.All rights reserved.  相似文献   

20.
In this paper, the stereodynamics of Li + DF → Li F + D reaction is investigated by the quasi-classical trajectory(QCT)method on the ^2A' potential energy surface(PES) at a relatively low collision energy of 8.76 kcal/mol. The scalar properties of the title reaction such as reaction probability and cross section are studied with vibrational quantum number of v = 1–6. The product angular distributions P(θr) and P(φr) are presented in the same vibrational level range. Moreover, two polarization-dependent generalized differential cross sections(PDDCSs), i.e., the PDDCS00 and PDDCS22+are calculated as well. These stereodynamical results demonstrate sensitive behaviors to the vibrational quantum numbers.  相似文献   

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