1 / 5

Lecture 4: Coupled Channel Approximation and the R-Matrix Codes

Lecture 4: Coupled Channel Approximation and the R-Matrix Codes. Recall: To solve the ( e+ion ) problem we compute ion wavefunctions first, independently using Superstructure or similar atomic structure code

apria
Download Presentation

Lecture 4: Coupled Channel Approximation and the R-Matrix Codes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 4: Coupled Channel Approximation and the R-Matrix Codes • Recall: • To solve the (e+ion) problem we compute ion wavefunctionsfirst, independently using Superstructure or similar atomic structure code • The coupled-channel (CC) approximation couples the free electron and ion wavefunctions • R-Matrix method is the most efficient for most atomic processes in plasmas

  2. “Stages” of the R-Matrix Codes • Superstructure (SS)  one-electron orbitals (sspnl), optmized over target ion wavefunctions • One and two-electron Slater integrals SS (sspnl)  STG1 • Angular algebra: STG2 reconstructs the target ion and couplings for the (e+ion) system STG1  STG2 (non-relativistic LS coupling) • STG2  RECUPD: Intermediate re-coupling LS  LSJ (Breit-Pauli approximation) • RECUPD  STGH: (e+ion) Hamiltonian Diagonalization

  3. Flow Chart: Sets of R-Matrix Codes • Non-relativistic R-Matrix and relativistic Breit-Pauli R-Matrix (BPRM): LS and LSJ coupling • R-Matrix II codes: “Complete” (e+ion) angular treatment; large number of levels • Dirac R-Matrix Codes (DARC): Use GRASP for target ion wavefunctions for high-Z systems • Fig. 3.9  Flow chart

  4. “Asymptotic” R-Matrix Codes • Following (e+ion) hamiltoniandiagonalization, STGH produces an H.DAT file which is utilized by subsidiary codes to calculate:  electron-ion cross sections (STGF)  (e+ion) bound state energy levels (STGB)  bound-bound transition probabities (STGBB)  bound-free (photoionization) cross sections (STGBF)

  5. Astrophysical Quantities • Absorption oscillator strengths and photoionization cross sections  Opacities • Line emissivities  Emission Line Diagnostics • All atomic parameters  Non-LTE radiative transfer models

More Related