Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] abhc_v1_0.gz(52 Kbytes)|
|Manuscript Title: Bound -> continuum intensities: a computer program for calculating absorption coefficients, emission intensities or (golden rule) predissociation rates.|
|Authors: R.J. Le Roy|
|Program title: BCONT|
|Catalogue identifier: ABHC_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 52(1989)383|
|Programming language: Fortran.|
|Operating system: UNIX VERSION 4.2, VMS VERSION 4.5.|
|Word size: 64|
|Keywords: Molecular physics, Scattering, Photon, Photodissociation, Absorption coefficient, Predissociation, Golden rule, Continuum emission.|
Nature of problem:
This program calculates the bound -> continuum transition intensities associated with photodissociation, spontaneous emission or predissociation from vibration-rotation levels of a single (bound) initial-state potential into continuum levels of one or two distinct final electronic states, and if desired, fits to experimental data to determine parameters characterizing the final-state potential and/or transition coupling functions.
For arbitrary smooth potentials, the radial or effective one-dimensional Schrodinger equation is solved using the Numerov algorithm to determine the discrete initial-state eigenvalue(s) and eigenfunction(s) and continuum final-state wavefunctions, which are used with the specified transition coupling functions to calculate the desired matrix elements.
Current dimensioning considerations permit consideration of transitions at up to 150 frequencies and the calculation and (if desired) fitting of data for thermal initial-state vibration-rotation populations corresponding to up to 4 temperatures. Simultaneous transitions to continua associated with up to two (uncoupled) final electronic states may be considered. The final state potential(s) and transition coupling function(s) are assumed to have particular forms (see long write up).
The running time depends entirely on the complexity of the calculation being performed. For example, a simple calculation of the predissociation rates for thirteen levels required 5 sec., while three cycles of an eight-parameter fit to thermal absorption coefficients for 26 frequencies at two temperatures required 776 sec. on a SUN-3/260 with floating point accelerator.
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