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Manuscript Title: A program to compute variationally optimized effective atomic potentials.
Authors: J.D. Talman
Program title: ATOMOPM
Catalogue identifier: ABHT_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 54(1989)85
Programming language: Fortran.
Computer: CYBER 835.
Operating system: NOS 2.5.
RAM: 38K words
Word size: 60
Peripherals: disc.
Keywords: Effective potential, Exchange potential, Optimized potential, Atomic physics, Structure.
Classification: 2.1.

Nature of problem:
The electrons in an atom can be regarded in an approximate way to be moving in a local potential that is determined by the nuclear charge and an average potential produced by all the electrons. This program calculates numerically the effective potential seen by the electrons in the atom using the variational principle. The resulting wave function is the best independent-particle wave function that can be constructed from a local, central potential, in the variational sense. Orbitals constructed from this potential may provide a good basis for further atomic structure calculations.

Solution method:
The variationally optimum potential satisfies a Volterra type integral equation of the first kind. The problem is solved self-consistently by starting with an initial potential, which can be taken to be zero, solving for the single-particle orbitals and energies, constructing the kernel and inhomogeneous term in the integral equation, and solving the integral equation numerically. The procedure is then iterated until a a self-consistency requirement is met. The procedure actually calculates only the exchange part of the potential; the direct or Hartree part of the potential is obtained in a straightforward way from the density.

Running time:
The program required 13 seconds to calculate the potential for the Na atom in 15 iterations at 100 mesh points on the Cyber 835.