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Manuscript Title: Frozen core Hartree-Fock program for atomic discrete and continuous states.
Authors: L.V. Chernysheva, N.A. Cherepkov, V. Radojevic
Program title: ATOMIC FROZEN CORE HARTREE-FOCK
Catalogue identifier: AAKZ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 18(1979)87
Programming language: Algol.
Computer: CDC 3600.
Operating system: SCOPE 6.3.
RAM: 32K words
Word size: 48
Keywords: Atomic physics, Self-consistent field, Hartree-fock (method), Independent-particle Approximation, Single-particle model, Structure electronic, Atomic models, Off-diagonal energy Parameters, Frozen core, Ground state, Excited state, Single-electron state, Discrete state, Continuous state, Single-configuration, Atomic shell, Nl-(sub)shell, Iteration (iterative process), Many-electron, Correlations, Electron configuration.
Classification: 2.1.

Subprograms used:
Cat Id Title Reference
AAKQ_v1_0 ATOMIC SCF HARTREE-FOCK CPC 11(1976)57

Nature of problem:
The present program calculates the excited state Hartree-Fock (HF) radial wave function of a single-electron in the 'frozen core' (FC) field of other electrons. The radial one-electron wave functions of the 'frozen core' are a soLUtion of the corresponding self-consistent field HF problem. The energy eigenvalue for single-electron discrete (bound) states, or the phase shift for continuous states are also calculated.

Solution method:
Being a linear integro-differential equation in FC HF equation is solved by iteratively solving the corresponding inhomogeneous differential equation. The differential equation is solved in the same way as in the self-consistent field HF program. The off-diagonal energy parameters are also determined iteratively, while the phase shift for the continuous state is obtained by integrating the differential equation outwards, beyond the cut-off radius, until the asymptotic behaviour is reached.

Restrictions:
It may happen that the present program does not give a solution for certain states for which it is known that some resulting off-diagonal energy parameters are approximatley equal to or greater, in absolute value, than the single-particle energy (i.e. the diagonal energy parameter), as for example, for single-particle state ns in the configuration 1 s squared 2sns (1S). The procedure for evaluation of the off-diagonal parameters does not then converge.

Unusual features:
The present program is so designed that the direct results of the self- consistent field HF program, stored on a magnetic tape, are taken for the FC states. The indepenent variable in both programs is x= alpha r + beta 1n r, which has behaviour suitable for both small and large values of the radii r.

Running time:
The total running time including compilation on the CDC 3600 computer with all peripherals connected on-line, for the excited state configurations of the nitrogen atom with 700 integration points is:
(i) about 25 min for 18 different vd radial functions of the configuration 1s squared 2s squared 2p squared vd(4P) (no evaluations of off-diagonal energy parameters);
(ii) about 60 min for 18 different vs radial functions of the configuration 1s squared 2s squared 2p squared vs (4P).