K. E. Banyard

University of Leicester

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G J Seddon

University of Cambridge

R. B. Hake

Massachusetts Institute of Technology

G. K. Taylor

University of Leicester

M. Dixon

University of Oxford

A D Tait

Statistics Canada

P K Youngman

University of Leicester

David R. T. Keeble

University of Nottingham Malaysia Campus

D J Ellis

University of Toledo

Jeffrey M. Sanders

Schrodinger (United States)

C E Reed

University of Leicester

Cooperative Institutions

University of Leicester

University of Oxford

Donostia International Physics Center

University of Antwerp

Science Oxford

The Abdus Salam International Centre for Theoretical Physics (ICTP)

Universidad de Valladolid

University of the Basque Country

Oak Ridge National Laboratory

John Wiley & Sons (United States)

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Charge exchange between simple structured projectiles in high-energy collisions

Physical review. A, General physics (1980)

K. E. Banyard G. W. Shirtcliffe

The continuum---intermediate-states approximation has been adapted for application to charge-exchange collisions between high-energy structured projectiles. A critical test of the scheme is provided by the reaction $\mathrm{H}(1s)+\mathrm{H}(1s)\ensuremath{\rightarrow}{\mathrm{H}}^{\ensuremath{-}}(1{s}^{2})+{\mathrm{H}}^{+}$; the overall agreement with the limited experimental data is encouraging.

Charge exchange

High energy

10.1103/physreva.22.1452

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Citations (18)

A calculation of the spectroscopic constants for several states of NF

Journal of Physics B Atomic and Molecular Physics (1974)

D J Ellis K. E. Banyard

Spectroscopic constants for NF are determined from a Dunham analysis of potential energy curves computed previously by means of a valence configuration interaction method. Results are presented for several experimentally known and unknown states within the 3 Sigma -, 1 Delta , 1 Sigma +, 1 Sigma -, 3 Delta and 3 Sigma + symmetry species. Where possible, our findings are compared with other calculations and with experiment.

Sigma

Force constant

10.1088/0022-3700/7/15/010

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Citations (7)

Electron correlation and elastic scattering cross sections for He

Journal of Physics B Atomic and Molecular Physics (1975)

K. E. Banyard G J Seddon

The systematic introduction of electron correlation into the ground-state description of He is examined from the viewpoint of its influence on the elastic scattering cross sections for the projectiles e-, H+, H, He+ and Li++ when determined within the first Born approximation.

Born approximation

Nuclear cross section

Electron scattering

Electronic correlation

10.1088/0022-3700/8/1/006

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Citations (4)

Electron capture from H^-by fast alpha particles

Journal of Physics B Atomic and Molecular Physics (1978)

K. E. Banyard J C Moore

Cross sections are reported for electron capture by fast alpha particles from H- ions. The calculations are based on the continuum-distorted wave approximation and the target is described by three separate wavefunctions, one of which is an extended configuration-interaction function. Several different capture states are considered and, in addition, values are presented for the total cross sections for all transitions. The influence of electron correlation is examined and the results are compared with those arising from the earlier proton-H- calculations. A brief comment is also made concerning cross sections for electron capture by mu + mesons.

Electron capture

Alpha particle

10.1088/0022-3700/11/22/017

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Citations (4)

Continuum-distorted-wave calculations for electron capture from hydrogen negative ions by fast protons

Journal of Physics B Atomic and Molecular Physics (1978)

J C Moore K. E. Banyard

The continuum-distorted-wave approximation has been used to determine the electron-capture cross sections sigma (nl,n'l') when fast protons impinge on the H- target system. The range of the projectile energy extends up to 2 MeV and the quantum labels (nl) and (n'l') denote the electronic states of the captured and passive electrons, respectively. The authors have considered the states n (and n')=1 and 2 with l=0, 1 and l'=0. From these results, values of the total capture cross section Sigma have been determined using the Oppenheimer n-3 rule. The target system is described, in turn, by a simple variational wavefunction, a Hartree-Fock function, a split-shell description, and finally, a configuration-interaction wavefunction which allows for over 99% of the electron correlation energy.

Sigma

Electron capture

Electronic correlation

10.1088/0022-3700/11/9/014

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Citations (18)

Electron correlation in momentum space: the ground state of Li(²S)

Journal of Physics B Atomic and Molecular Physics (1987)

K. E. Banyard P K Youngman

Electron correlation is examined in momentum space for the individual intra- and inter-shell electron pairs in the ground state of Li(2S). It is established that the radial and angular components of the correlation have opposing influences on the inter-particle momentum distributions f(p12) and g(p12;p1), where p12= mod p1-p2 mod and p1= mod p1 mod . By examining the Coulomb shifts Delta f(p12) and, in particular, the partial Coulomb shifts Delta g(p12;P1) for each electron pair, such a feature enables one to identify the major component of correlation in different regions of momentum space. This represents a distinct advantage over the more traditional position space approach. For K alpha K beta , not only was it found that intra-shell correlation effects were influenced by the occupation of the 2s orbital but, more interestingly, the nature of the influence was seen to change markedly throughout different regions of space. For the K alpha L alpha and K beta L alpha inter-shells, the importance of angular correlation was highlighted and, for K alpha L alpha , the consequence of the Fermi effect was observed. Comparisons were made with a previous, and complementary, position-based study of Li(2S) and with the correlation effects found in momentum space for closed shell Li+(1S) and Be(1S).

Electronic correlation

Momentum (technical analysis)

Electron pair

10.1088/0022-3700/20/21/011

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Citations (22)

Central-Field Approach for NH3 and H2O

The Journal of Chemical Physics (1957)

K. E. Banyard N. H. March

First Page

10.1063/1.1743900

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Citations (10)

Coulomb correlation in the 2¹S, 2³S, 2¹P and 2³P states of He

Journal of Physics B Atomic and Molecular Physics (1982)

K. E. Banyard P K Youngman

Electron correlation has been examined in detail for the 21S, 23S, 21P and 23P states of He and comparisons are made with the ground state. The correlated and Hartree-Fock descriptions of these (1s, nl) excited states are provided by the wavefunctions of Tweed (1973) and Davidson (1965), respectively. Coulomb holes, various partial Coulomb holes and several one- and two-particle expectation values are presented. The concept of partial Coulomb holes and their collective presentation has surfaces as been demonstrated to be particularly informative. These surfaces enabled us to interpret correlation effects in different regions of space and so provide a rationalisation of the correlation mechanisms in each state. For all four states, correlation caused a significant inward shift of density from the outer regions due to a reduction in nuclear shielding. However, in the inner regions around the nucleus, the influence of correlation was more complicated and depended not only on the multiplicity of the state but also on its symmetry.

Electronic correlation

10.1088/0022-3700/15/6/011

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Citations (17)

Momentum space and Coulomb correlation: A two-particle density analysis for the H2(1Σ+g) molecule

The Journal of Chemical Physics (1993)

K. E. Banyard Jeffrey M. Sanders

Electron correlation in momentum space is assessed for the ground-state of H2 by examining changes in the two-particle probability density evaluated over preselected momentum planes. The associated radial and angular ‘‘planar Coulomb shifts,’’ ΔR(p12) and ΔA(εp), are also calculated. This study complements an earlier analysis for H2 in position space. The natural expansion of the correlated wave function used previously was converted into momentum space by means of a Dirac–Fourier transform. As before, correlation effects are measured with respect to the description provided by the first natural configuration. Characteristics of the three components of Coulomb correlation for a linear molecule are highlighted by specific choices for the momentum of a ‘‘test’’ or ‘‘reference’’ electron. Unlike position space, it was found that one component worked in distinct opposition to the other components, a feature analogous to atomic studies in momentum space. The trends observed throughout a series of probability changes in momentum space for H2 were rationalized and linked to the correlation behavior in position space.

Momentum (technical analysis)

Position (finance)

10.1063/1.465997

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Citations (14)

Electron capture from lithium and its ions by high-energy protons

Journal of Physics B Atomic and Molecular Physics (1979)

K. E. Banyard G. W. Shirtcliffe

The continuum-distorted wave method is used to calculate cross sections for electron capture by fast protons from the lithium atom and its related positive ions. With the exception of Li2+(12S), each target electronic state is described by a Hartree-Fock wavefunction. For the lithium atom, capture can occur from either the K or L shell and the resulting ion can exist either in its ground state 11S or in one of the excited states 21S or 23S; cross sections are tabulated for each of these states for capture into the hydrogen levels (nl). Results for the individual capture states (nl) are also reported for the Li+ target. Total capture cross sections are calculated for each target by means of the Oppenheimer n-3 rule. For Li and Li+, total cross sections are also evaluated at E<200 keV. A procedure for determining the effective screening of the target nucleus by the uncaptured electrons is discussed and the sensitivity of the cross sections with respect to such screening is examined.

Electron capture

Lithium atom

Hydrogen atom

10.1088/0022-3700/12/19/010

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Citations (30)