D. W. Norcross

Pseudopotential calculations for Na2+, Na and Na2−

Abstract Potential curves have been computed for five states of Na 2 + , five states of Na 2 and two states of Na 2 − using a pseudopotential approach. The results are consistent with the accepted attribution to a 3 Π state of the perturbations observed in transitions involving the A 1 Σ u state of Na 2 , and the stability of the Na 2 − ion is established.

Asymptotic solutions of the coupled equations of electron-atom collision theory for the case of some channels closed

Solutions of coupled equations for electron-atom collision theory, having known asymptotic forms, can be calculated using asymptotic expansions at some large values of r, say r=rp and rp+1. At some smaller values of r, say r=r1 and r2, it is required to match the asymptotic solutions to solutions which are bounded at the origin. When some channels are closed, inwards integrations from (rp,rp+1) to (r1,r2) can give solutions which have poor linear independence at (r1,r2). It is shown that good linear independence can be obtained using a Fox-Goodwin technique for the solution of two-point boundary value problems.

The scattering of electrons by sodium atoms

Four state exchange (3s-3p-4s-3d) close coupling equations are solved for the scattering of electrons by sodium atoms at incident energies up to 5 eV. The results are presented in such a form that a number of different measurable quantities may be readily extracted from tables and simple formulae. Total and differential (elastic and inelastic) cross sections, and the polarization of the resonance doublet radiation, are calculated. Results obtained do not differ to any great extent from two state (3s-3p) calculations of the same quantities. Comparison with available experimental data is made; the total cross section disagrees with the experiment of Brode (1929); and the results obtained for the polarization of the radiation fail to remove the discrepancy between the experiment of Hafner and Kleinpoppen (1967) and the two state calculations by Karule (1970). The polarization agrees well with more recent experimental results, as do the differential elastic scattering and 3s to 3p excitation cross sections.

Recent Developments in the Theory of Electron Scattering by Highly Polar Molecules

Publisher Summary This chapter summarizes recent work in the theory of electron collisions as applied to highly polar molecules. In the discussion of both theory and calculations presented in the chapter, the emphasis is on elastic scattering and rotational excitation; however, vibrational excitation is also discussed briefly. The chapter presents a general overview of the unique features of scattering by polar molecules with a view to motivating and providing direction for the discussion to follow. The chapter is also devoted to a synthesis of the formal theoretical hardware, to numerical techniques that are essential to scattering calculations, and to an adequate description of the interaction potential. The chapter emphasizes on the approaches that employ the most powerful and general techniques. Discussions and comparisons of some of the recent applications of this machinery, the various approximations made thereto, and the general physical picture thus developed are presented in the chapter.

Bound electronic states of HCl

This paper reports ab initio Born–Oppenheimer calculations on the X 1Σ state of HCl and on the 1 2Σ, 2 2Σ, and 2Π states of HCl− for internuclear distances at which these states are electronically bound. The calculations employed square‐integrable configuration interaction wave functions which included all single and double replacements from multiconfiguration reference functions. The MC‐SCF reference configurations and the Gaussian atomic basis encompass the dominant effects which govern the electronic states studied. In the process of these calculations, we have calculated the static polarizability of Cl− and reproduced the known polarizabilities of H, Cl, and H−. The calculations on the X 1Σ state of HCl yield a De within 0.10 eV of the measured value, and ωe within 3 cm−1 of the measured value. For the molecular ion, we find the potential of the 1 2Σ state of HCl− to be attractive and to undergo substantial charge transfer, and the potentials of the 2Π and 2 2Σ states to be repulsive even at large int...

Low energy elastic scattering of electrons by Li and Na

Resonance structure previously obtained in low energy phase shifts for elastic scattering of electrons by Li and Na for total L=0 is shown to be the consequence of a lack of uniqueness in the asymptotic solutions of the coupled equations. An algorithm is developed for obtaining unique asymptotic solutions, and new low energy phase shifts computed. A modified form of the scaled Thomas-Fermi statistical model potential including core polarization is used for the target in the coupled equations formulation of the scattering problem. The results conform to the well known modified effective range formula, and exhibit no resonance structure whatsoever.

Energy levels for Be I calculated using a model potential and cores approximations

A two-electron model Hamiltonian, used for Be I, includes a core polarization potential Vpol(1,2) which has asymptotic form Vpol approximately - alpha ((r1/r12)+(r2/r22))2 where alpha is the polarizability of Be III 1s1. Solutions are obtained using a frozen-cores method. Two approximations are considered: (a) uses an expansion with core states Be II 2s and 2p; (b) includes in addition a 3d core orbital with a parameter determined variationally. For the series 1S, 3S, 1P0, 3P0, 1D, 3D, 1F0 and 3F0, results are obtained for all bound states ( epsilon 0. For the series 1P, 3P, 1D0, 3D0 converging to Be II 2p, results are obtained for n<or=10 and for n= infinity . The calculated ionization energies are more accurate than those obtained in previous theoretical work.

Electron collisions with highly polar molecules: integrated and momentum transfer cross sections and conductivity integrals for KOH and CsOH

The authors report close-coupling calculations of the total integrated and momentum transfer cross sections for the scattering of electrons from KOH and CsOH in the energy range 0.01 to 10 eV. A cut-off dipole potential is used to account for the long-range interaction. The authors nominally chose the cut-off radius Rc such that the potential has a minimum in the vicinity of the nucleus nearest to the centre-of-mass (COM) of the molecule. The results for the total integrated and momentum transfer cross section exhibit oscillations about a mean value. The choice of a different value for Rc in additional calculations for KOH led to results for the mean value and amplitude which were virtually identical for k2<<1/(2rc)2. A simple semi-quantitative understanding of this behaviour is presented in the context of Fabrikants effective-range theory (ERT). Analytical expressions are given for the interaction parameters (conductivity integrals) which may be used for calculating electrical properties of gas mixtures according to the popular algorithm of Demetriades and Argyropoulos (1966).

Photoionization of the He metastable states

Solutions of the coupled equations for e-He+ scattering are used as final states in the matrix element for photoionization of metastable He. Results are given for both the elastic and inelastic scattering regions of He+, including oscillator strengths for photoexcitation of the lowest few resonance states of He.

Oscillator strengths for thallium calculated using a semiempirical relativistic one-electron central-field model potential

Abstract The results of calculations for oscillator strengths, radiative transition probabilities and excited state lifetimes are presented and compared with those of other calculations and measurements. The agreement with measured oscillator strengths is generally quite good. The importance of core polarization effects for the diffuse series is demonstrated. The significance of the results for measurements of parity-nonconserving effects due to weak neutral currents is discussed.