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[Licence| Download | New Version Template] aanc_v3_0.tar.gz(274 Kbytes)
Manuscript Title: Standalone relativistic continuum wavefunction solver.
Authors: M.G. Tews, W.F. Perger
Program title: CONTWVSA version 1.0
Catalogue identifier: AANC_v3_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 141(2001)205
Programming language: Fortran.
Computer: Digital Personal Workstation 500, Intel i386.
Operating system: Digital UNIX V4.0D, LINUX RedHat 6.2.
RAM: 19M words
Word size: 8
Keywords: Continuum wavefunctions, Relativistic effects, Dirac-Fock, Atomic physics, Structure.
Classification: 2.1.

Nature of problem:
The relativistic Dirac-Fock equations are set up and solved numerically for continuum wavefunctions.

Solution method:
Relativistic atomic wavefunctions are calculated using a central differences method with deferred corrections. The grid spacing at large radial distances (the linear region of the two-piece grid) is automatically determined to provide at least 10 grid points per half cycle of the wavefunction. Lagrange multipliers are automatically calculated without additional input. Extra angular coefficients are read from a separate input file.

Reasons for new version:
The new version is required for obtaining relativistic continuum orbitals for a wider range of configurations.

Summary of revisions:
This new version is independent of the GRASP package [1]. Additional angular structure needed for some open shell systems is now read from an extra input file. The convergence behavior is improved by choosing a hydrogenic continuum wavefunction as starting point for the self-consistent field process and the possibility of using a previously calculated continuum orbital as starting point is included.

Restrictions:
Continuum orbitals for atoms ranging from hydrogen to mercury have been calculated, with up to six Lagrange multipliers and energies from zero to 100 atomic units. Cases outside of these limits will likely also succeed.

Unusual features:
The program will calculate a virtual state V**(B-1) continuum orbital for a given K quantum number and dump that orbital to a file. The program uses a relativistic WKB approximation for normalization of the continuum orbital in the presence of a non-neural core and it uses a curve-fitting procedure for normalization in the case of a neutral core. The spacing of the radial grid at large radial distances, where the two-piece grid is linear, is automatically calculated to provide at least 10 grid points per half cycle. Additional angular structure needed for some open shell systems is read from an extra input file to enhance the set of treatable systems. For better convergence the possibility of using a previously calculated continuum orbital as starting point for the self-consistent field process has been included.

Running time:
The typical running time is 10 seconds to 1 minute on a Digital-Personal Workstation model 500.

References:
[1] K.G. Dyall, I.P. Grant, C.T. Johnson, F.A. Parpia, E.P. Plummer, Comput. Phys. Commun. 55 (1989) 425.