Model potential for calculation of multiphoton processes in diatomic molecules

The model potential, analogous to the Fues atomic potential is suggested for analytical calculation of the perturbation theory matrix elements, defining interaction of molecule with electromagnetic field. The explicit expressions for the Green and wave functions of the molecular optical electron are received.     

The calculation of potential energy curves of diatomic molecules: Application to halogen molecules

Methods for computing the vibrational turning points of diatomic molecules are summarized. An extension of the technique described by Vanderslice et al. is used to derive simple analytical expressions for calculation of the turning points from spectroscopic data. For most molecular states, the method gives results in agreement with those from sophisticated numerical procedures. Recently available spectroscopic data have been used to determine the potential energy curves for the¹∑⁺_g and ³Π(0⁺_u) states of Cl₂ and Br₂.     

Estimation of rotational and vibrational constants for diatomic molecules using Mattera's potential function

Summary The potential function suggested by Mattera, Salvo, Terreni and Tommasini is investigated further and the expressions for rotational constant α_e and anharmonicity constantw _e x _e are obtained. The α_e andw _e x _e values of twentyseven diatomic molecules are calculated using those expressions and they are compared with their experimental values.     

Rotational and vibrational excitation of sputtered diatomic molecules

The rotational and vibrational level population distributions of ground and electronically excited states of several homonuclear and heteronuclear molecules are calculated for direct ejection, association, and associative ionization mechanisms of molecule sputtering. The cascade properties, formation mechanism, initial atom separation, and axis orientation to the surface are clearly reflected in the sputtered molecule distributions. In general, extensive non-Boltzmann rotational and vibrational distributions are predicted. The probability that an atom pair survives the ejection, for typical sputtering parameters, is high; approximately 50% for homonuclear molecules to near 100% for hydrides. The predictions are compared with experimental optical emission spectra in the accompanying paper.     

High order Correlation polarization potential for vibrational excitation scattering of diatomic molecules by low-energy electrons

This paper introduces a correlation--polarization potential with high order terms for vibrational excitation in electron--molecule scattering. The new polarization potential generalizes the two-term approximation so that it can better reflect the dependence of correlation and polarization effects on the position coordinate of the scattering electron. It applies the new potential on the vibrational excitation scattering from N₂ in an energy range which includes the ²П_g shape resonance. The good agreement of theoretical resonant peaks with experiments shows that polarization potentials with high order terms are important and should be included in vibrational excitation scattering.     

On the calculation of matrix elements in diatomic molecules

Group theoretical techniques similar to those employed for transition-metal complexes are applied to diatomic molecules. Expressions are given for reduced matrix elements between configurations with one, two and three electrons outside closed shells. The results agree with previous calculations but predict deviations from simple applications of the hypothesis of pure precession.     

Studies on dissociation energies of diatomic molecules using vibrational spectroscopic constants

New analytical expression and numerical approach are suggested to calculate dissociation energies De of diatomic molecular states using an extreme value method (EVM). Studies on some electronic states of OH, BH, N2, Br2, ClF and CO molecules show that the accuracy of the EVM dissociation energies depends on the number of correct vibrational constants used in the calculations. The convergence qualities of De are suggested to be an alternative physical criterion to measure the qualities of the various sets of vibrational constants from different literature for the same diatomic state.     

双原子分子振动能谱与离解能的精确研究

代数方法(AM)的建立解决了实验方法和精确量子力学理论方法难以获得双原子分子的包含最高振动能级在内的所有高阶振动能级的精确数值这一问题.基于LeRoy与Bernstein的工作,孙卫国等又建立了精确计算双原子分子离解能的新解析表达式.应用新公式和代数方法(AM),研究了一些双原子分子部分电子态的振动能谱和分子离解能,获得了与实验值符合非常好的理论结果.该方法在理论上提供了获得双原子分子完全振动能谱和精确分子离解能的物理新方法.     

分立位置表象中双原子分子振动能级的计算

用离散的位置基矢作为连续位置基矢的近似,构建分立位置表象.在分立位置表象中,哈密顿算符矩阵具有对角占优、带状稀疏的特点,矩阵元不用做积分运算,具有特别简单的解析表达式.分别对双原子分子在Morse势、Murrell-Sorbie势和双阱势中运动情形,进行了数值计算.结果表明,在分立位置表象中计算双原子分子振动能级,方法简便,稳定性好,计算精度高.     

Hypervirial calculation of perturbed—Morse-oscillator potentials for diatomic molecules

The rotational-vibrational behavior of diatomic molecules has been studied using a hypervirial treatment for the perturbed Morse oscillator (PMO). Relations needed to calculate the PMO parameters from spectral data are derived. Rotational effects are included and the Dunham coefficients are obtained in terms of model parameters. The procedure is applied to CO in the ground-electronic state and the results are compared with others available data.     

A new Morse ring-shaped potential for diatomic molecules

Using the Pekeris approximation, the Schrödinger equation is solved analytically for the Morse plus a novel angle-dependent potential. The generalized parametric Nikiforov–Uvarov method is used to obtain energy eigenvalues and corresponding eigenfunctions. We present the effect of the angle-dependent part on radial solutions, and some numerical results for diatomic molecules are also given.     

Systematics of vibrational intensities for “diatomic” molecules: Approximate formulas

Several approximations are discussed which enable one to estimate electric dipole moment transition matrix elements for diatomic molecules based on a very limited amount of experimental data. For strongly polar molecules, a simplistic point-charge dipole model in which there is no vibrational charge flux predicts a simple relation between the permanent moment, M₀, and its derivative with respect to internuclear separation, M₁. This is found to be approximately valid for a surprisingly large number of polar molecules. Next, approximate matrix elements for the fundamental and overtone bands are presented for a linear dipole moment function. Finally, systematic trends for molecules having similar electronic structures are investigated and combined with the approximations discussed above in order to estimate the transition moments for several molecules of astrophysical interest. An extension to the ν₃ fundamental and overtone bands of CH₄ is suggestive that some of these ideas may be applicable to certain polyatomic molecules as well.     

Effect of stretching on intermolecular potentials of diatomic molecules

The effect of stretching due to rotations and vibrations on the intermolecular potentials of diatomic molecules has been considered. The calculations for nitrogen and oxygen on the Lennard-Jones (12:6) model show that the effect is significant. Consequently, for polyatomic molecules the effect of stretching must be considered for a correct representation of the intermolecular potential.     

Theory of pressure-induced vibrational and rotational absorption of diatomic molecules at high temperatures

A derivation is given for the integrated absorption coefficient of pressure-induced pure rotational and vibrational transitions in binary collisions of homonuclear diatomic molecules of the same chemical species. The previously neglected effects of excited vibrational states, mechanical anharmonicity, and vibration-rotation interaction are taken into account to obtain more accurate absorption coefficients at high temperatures. In the region of the fundamental wave number the excited vibrational states make more of a contribution to the absorption than their relative population would lead one to expect.     

Highest rotational and vibrational excitation of swift diatomic molecules scattered by solid surface

It is shown that at nondissociative scattering of swift molecules by solid surface and inverse population of the highest rotational and some vibrational states unattainable at thermal excitation could be achieved. For single crystal surface a specific polarization and orientational effects in rotational and vibrational excitation of the scattered molecules could be observed.