Farm — A flexible asymptotic R-matrix package

Burke, V.M.; Noble, C. J.

doi:10.1016/0010-4655(94)00178-5

Cited by 147 publications

(104 citation statements)

References 20 publications

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“…The cross sections of interest were then obtained in the same way as in the standard R-matrix approach. We employed an updated version [14] of the flexible asymptotic R-matrix (FARM) package by Burke and Noble [15] to solve the problem in the asymptotic region and to obtain the transition matrix elements of interest. After transforming the latter from the present jj -coupling to the jlK-coupling scheme and also accounting for the appropriate phase convention of the reduced matrix elements, we employed the program MJK of Grum-Grzhimailo [16] to calculate the results shown below.…”

Section: Theorymentioning

confidence: 99%

High-resolution experiments andB-splineR-matrix calculations for elastic electron scattering from krypton

2011

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In a joint experimental and theoretical effort, we carried out a detailed study of elastic electron scattering from Kr atoms. Absolute angle-differential cross sections for elastic electron scattering were measured over the energy range 0.3−9.8 eV with an energy width of about 13 meV at scattering angles between 0 • and 180 • . Excellent agreement is obtained between our experimental data and predictions from a fully relativistic Dirac B-spline R-matrix (close-coupling) model that accounts for the atomic dipole polarizability through a specially designed pseudostate.

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Section: Theorymentioning

confidence: 99%

High-resolution experiments andB-splineR-matrix calculations for elastic electron scattering from krypton

2011

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“…The internal region problem is solved using the the RMATRX1 code (Berrington et al 1995), and the external region scattering problem is solved using the FARM code (Burke & Noble 1995). These papers, and references therein, should be consulted for detailed descriptions of the theory and the codes.…”

Section: Calculationsmentioning

confidence: 99%

Electron-impact excitation of neutral oxygen

Barklem¹

2006

A&A

105

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Aims. Our goal was to calculate transition rates from ground and excited states in neutral oxygen atoms due to electron collisions for non-LTE modelling of oxygen in late-type stellar atmospheres, thus enabling the reliable interpretation of oxygen lines in stellar spectra. Methods. A 38-state R-matrix calculation in LS -coupling has been performed. Basis orbitals from the literature are adopted, and a large set of configurations are included to obtain good representations of the target wave functions. Rate coefficients are calculated by averaging over a Maxwellian velocity distribution. Results. Estimates for the cross sections and rate coefficients are presented for transitions between the seven lowest LS states of neutral oxygen. The cross sections for excitation from the ground state compare well with existing experimental and recent theoretical results.

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“…An extensive LS collision study was carried out including 27 doublet and quartet levels arising from the 3d 9 , 3d 8 4s and 3d 8 4p Ni ii basis configurations, a much larger close coupling (CC) expansion than that adopted by Bautista & Pradhan (1996). LS collision strengths were computed using the external region R-matrix package FARM (Burke & Noble 1995). Although fine-structure collision strengths were not computed in this work, the presence of prominent and complex resonance structures would undoubtedly enhance the effective collision strengths, suggesting that they should be greater than those previously calculated by both Nussbaumer & Storey (1982) and Bautista & Pradhan (1996).…”

Section: Introductionmentioning

confidence: 99%

Electron-impact excitation of Ni II

Ramsbottom¹,

Hudson²,

Norrington³

et al. 2010

A&A

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Context. Considerable demand exists for electron excitation data for Ni ii, since lines from this abundant ion are observed in a wide variety of laboratory and astrophysical spectra. The accurate theoretical determination of these data can present a significant challenge however, due to complications arising from the presence of an open 3d-shell in the description of the target ion. Aims. In this work we present collision strengths and Maxwellian averaged effective collision strengths for the electron-impact excitation of Ni ii. Attention is concentrated on the 153 forbidden fine-structure transitions between the energetically lowest 18 levels of Ni ii. Effective collision strengths have been evaluated at 27 individual electron temperatures ranging from 30-100 000 K. To our knowledge this is the most extensive theoretical collisional study carried out on this ion to date. Methods. The parallel R-matrix package RMATRX II has recently been extended to allow for the inclusion of relativistic effects. This suite of codes has been utilised in the present work in conjunction with PSTGF to evaluate collision strengths and effective collision strengths for all of the low-lying forbidden fine-structure transitions. The following basis configurations were included in the target model -3d 9 , 3d 8 4s, 3d 8 4p, 3d 7 4s 2 and 3d 7 4s4p -giving rise to a sophisticated 295 j j-level, 1930 coupled channel scattering problem. Results. Comprehensive comparisons are made between the present collisional data and those obtained from earlier theoretical evaluations. While the effective collision strengths agree well for some transitions, significant discrepancies exist for others.

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Farm — A flexible asymptotic R-matrix package

Cited by 147 publications

References 20 publications

High-resolution experiments andB-splineR-matrix calculations for elastic electron scattering from krypton

High-resolution experiments andB-splineR-matrix calculations for elastic electron scattering from krypton

Electron-impact excitation of neutral oxygen

Electron-impact excitation of Ni II

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