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王友年  李宏伟 《物理学报》2002,51(4):857-862
研究了快速双原子分子离子在固体中穿行时,尾流效应对各离子电荷态以及库仑爆炸过程的影响.借助于线性介电响应理论和局域介电函数,离子之间的动力学相互作用势可以表示成对称的屏蔽库仑势和非对称的尾势.通过对分子离子上所有束缚电子的总能量进行变分和求解单个离子的运动方程,自洽地确定出分子离子中每个离子的电荷态.数值结果表明,由于尾流效应的影响,在初始穿行阶段,分子离子中导航离子的电荷数随穿行深度的增加而单调递增,而尾随离子的电荷数则随穿行深度的增加而振荡.但当穿行深度很大时,两个离子的电荷数都趋于具有相同速度的孤立离子的电荷数.此外,还发现分子轴的取向朝入射速度方向偏转.  相似文献   

3.
Relativistic central-field (Dirac-Slater) calculations of photoionization of atoms and ions have been performed. The results show that the photoionization cross sections for inner-shell njl electrons are largely unaffected by removal of outer shell electrons (with principal quantum number greater than n) except for a shift in threshold, just as in the non-relativistic case. The most dramatic results are obtained for Th(Z=90) compared with Th80+ where σ(hv) remains almost constant through 80 stages of ionization. The results are explained in terms of the fact that 〈r〉 is primarily a function of principal quantum number.  相似文献   

4.
The one-photon transition probabilities in hydrogen-like ions are calculated for nuclear charge numbers in the range 1 ≤ Z ≤ 100. The calculations are performed in the framework of the relativistic Dirac’s theory for the states with the principal quantum numbers n = 2,3, 4. The finite nuclear size effect is taken into account. The role of the quantum electrodynamics (QED) and nuclear recoil corrections is also considered.  相似文献   

5.
The N.M.R. spectra of meta dichloro and meta dibromo benzenes are analysed in the nematic phase of 4-methoxy benzylidene-4-amino-α-methyl cinnamic acid-n-propyl ester at room temperature.

The direct couplings are found to be of negative sign. The molecules orient preferentially with the aromatic plane along the direction of the magnetic field and the C 2-symmetry axis perpendicular to it.

The relations between the various direct couplings and the inter-proton distances are reported. The ratio of the distance between the meta protons along the axis perpendicular to the C 2 symmetry and the ortho protons is determined precisely. The other ratios could not be determined to any reasonable precision. The reasons are discussed.

The angles between the C-H bonds of the equivalent protons and the C-C bonds in both the molecules are determined on the assumption of the C-H bond lengths and the ring geometry of benzene.  相似文献   

6.
A model based on the strong-field and Born-Oppenheimer approximations qualitatively describes the distribution over vibrational states formed in a diatomic molecular ion following ionization of the neutral molecule by intense laser pulses. Good agreement is found with a recent experiment [X. Urbain et al., Phys. Rev. Lett. 92, 163004 (2004)]. In particular, the observed deviation from a Franck-Condon-like distribution is reproduced. Additionally, we demonstrate control of the vibrational distribution by a variation of the peak intensity or a change of frequency of the laser pulse.  相似文献   

7.
Electron-impact ionization cross-sections and rate coefficients of the 1s ground state for H-like C, O, Mg, Ar, Fe, Cu, As, Kr, Y, Mo ions with incident electron energies up to 15 times the ionization threshold energy have been systematically calculated by the relativistic distorted-wave Born exchange (DWBE) approximation. The comparison of the result with the experimental data, other theoretical calculations and recommended values shows the very good agreement. The influence from relativistic and the lowest order QED effect in the calculation is discussed. The calculated ionization cross-sections are fitted by empirical formulas. These fits can be readily integrated over a relativistic Maxwellian electron distribution function to obtain rate coefficient for plasma modeling.  相似文献   

8.
The first accurate studies on the vibrational spectroscopic constants and the corresponding full vibrational energy spectra of some electronic states of diatomic molecular ions XY+ were performed using algebraic method(AM). The AM is applied on the X1Σ+ state of BeH+, the X2Σ+ state of CO+, the X2Πg state of F 2 + , the A2Πu state of O 2 + and the X2Σ g + state of Li 2 + . The results show that AM can generate accurate vibrational spectroscopic constants as well as accurate full vibrational energy spectra by using some accurate experimental vibrational energies, and that the AM vibrational energies are better than other theoretical data. __________ Translated from Chinese Journal of Atomic and Molecular Physics, 2005, 22 (4) (in Chinese)  相似文献   

9.
Absolute g-tensor calculations for planar hydrocarbon and for non-planar phenyl substituted hydrocarbon radicals are reported. The relevant interactions determining g are discussed. Calculations are performed on the basis of a second-order perturbation expansion. The electronic wavefunctions are obtained from a simplified version of Hoffmann's extended Hückel model (SEH), where all valence electrons are taken into account explicitly. For planar systems the observed linear dependence of g on the energy of the half filled π orbital is well reproduced. A qualitative analysis of this dependence, making restrictive assumptions about the σ electrons, was given earlier by Stone. The calculations for non-planar model systems reproduce the g-factor anomalies which are observed for highly twisted phenyl substituted hydrocarbon radicals. The results show the necessity of direct π-σ mixing and are consistent with recent investigations of the proton hyperfine couplings in such systems.  相似文献   

10.
Relativistic quantum calculations which include spin-orbit interactions and correlations were carried out for the low-lying states of ICl. Spectroscopic properties (R3, ωe, Te) were calculated for these states. Based on the energies and wave functions both the absorption and emission spectra of ICl in the region below 45000 cm−1 were interpreted. These calculations confirm the predissociation of the B0+ state and the existence of a second minimum (B′0+) in the 0+(II) state. Properties of the 0(I)(3Π0) state which is yet to be observed were also predicted. The calculated properties for the 2(I)(3Π2) state are in very good agreement with the properties obtained by the very recent characterization of the A′ state by optical three-photon resonance. The continuous and diffuse absorption spectra of ICl in the region below 45000 cm−1 were interpreted and assigned to the appropriate electronic transitions.  相似文献   

11.
The study of the isoscalar giant monopole resonance (ISGMR) should allow extracting a value for the nuclear incompressibility coefficient K. In this contribution, we review the most recent attempts along this line. While the nonrelativistic (Skyrme, Gogny) models predict K to be around 220–235 MeV, the values obtained from the relativistic calculations are significantly larger (250–270 MeV). We argue that the most plausible reason for this discrepancy lies in the different behavior of the symmetry energy in the two classes of models. We also discuss the role of the isoscalar giant dipole resonance (ISGDR). We conclude that a number of experimental ambiguities still prevent us from deducing K from the ISGDR with a comparable accuracy as from the ISGMR.  相似文献   

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Alexei M. Frolov   《Physics letters. A》2007,370(5-6):485-490
The bound state properties and general structure of some H+3-like molecular ions are determined from the results of direct numerical computations. All our calculations are performed with the use of non-adiabatic variational expansion written in the basis of five-body (= ten-dimensional) gaussoids. A large number of geometrical properties and expectation values of many inter-particle delta-functions are presented for the H2D+, H2T+, D2H+, D2T+, T2H+, T2D+ and HDT+ two-electron five-body ions. The problem of inter-particle correlations in five-body systems and related problem of adiabatic divergence in the H+3-like ions are also briefly discussed.  相似文献   

14.
W.D. Hobey 《Molecular physics》2013,111(4):325-331
In dealing theoretically with the effects of vibronic interactions in substituted benzene mononegative radical-ions it is useful to know the spin density distributions in the degenerate ground level of unsubstituted benzene anions. A configuration interaction theory is developed for hydrocarbon anions with degenerate ground states and applied to the benzene anion problem. The results show negative spin densities on atoms having zero spin density in the Hückel approximation.  相似文献   

15.
In this work,the existence of Borromean states is discussed for bosonic and fermionic cases in both therelativistic and non-relativistic limits from the 3-momentum shell renormalization.With the linear bosonic model,we check the existence of Efimov-like states in the bosonic system.In both limits a geometric series of singularities is found in the 3-boson interaction vertex,while the energy ratio is reduced by around 70%in the relativistic limit because of the anti-particle contribution.Motivated by the quark-diquark model in heavy baryon studies,we have carefully examined the p-wave quark-diquark interaction and found an isolated Borromean pole at finite energy scale.This may indicate a special baryonic state of light quarks in high energy quark matter.In other cases,trivialresults are obtained as expected.In the relativistic limit,for both bosonic and fermionic cases,potential Borromean states are independent of the mass,which means the results would also be valid even in the zero-mass limit.  相似文献   

16.
《Physics letters. A》2006,352(3):239-241
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17.
Potential energy curves (PECs) of the ground and the low-lying excited states of the InI molecule are computed using the internally contracted multireference singles and doubles configuration interaction with the Davidson correction (ic-MR-CISD + Q) method based on the relativistic effective core potentials (RECPs). The spectroscopic constants are obtained, including the excitation energy (T e), the equilibrium bond distance (R e), the dipole moment (μe) and the vibrational constants (ωe and ωe). Finally, we predict the transition dipole moments, the radiative lifetimes, and the Franc-Condon factors for the transitions of A3Π0+ ? X1Σ0 + and B3Πl ? X1Σ0 +,. The results reveal that A3Π0+ and B3Πl are long-lived states with the lifetimes being of the order of microseconds.  相似文献   

18.
The second-order WKB quantization condition is used to derive expressions for the second-order contributions to the vibrational energy levels and the rotational and centrifugal constants of a diatomic molecule. The second-order corrections to the RKR (Rydberg-Klein-Rees) turning points are also calculated. These second-order quantities are related to the quantities calculated from Kaiser's modified first-order quantization condition. Numerical calculations for the ground electronic state of carbon monoxide are compared with quantum-mechanical values obtained by numerical solution of the Schrödinger equation. In general, the second-order semiclassical values are in good agreement with the quantum-mechanical values, and can be computed by the present methods in a small fraction of the time.  相似文献   

19.
A new simple analytical diatomic potential energy function that can be considered an extension of the prototypical Lennard-Jones model is proposed and tested. Five- and six-parameter models are considered and these can be easily constructed from widely available low-order vibrational-rotational constants and the dissociation energy. Accuracy tests are carried out on the ground electronic states of sixteen diatomic molecules. The proposed six-parameter function is found to be more accurate than other available few-parameter analytical models for the diatomic potential energy, and has accuracy comparable to that of modern high-level ab initio functions.  相似文献   

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