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Manuscript Title: Computation of charge transfer probability between protons and excited hydrogen atoms.
Authors: V. Malaviya
Program title: H+ + H(2) CHARGE TRANSFER
Catalogue identifier: ACQQ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 1(1970)380
Programming language: Fortran.
Computer: ICL 1907.
Operating system: QUBE.
RAM: 25K words
Word size: 24
Keywords: Atomic physics, Molecular physics, Scattering, Impact parameter, One-electron wave Function, Charge transfer, Momentum transfer, Overlap and Interaction matrices, Matrix inversion, Perturbed energy, Lcao approximation, Schrodinger equation, Molecular states, Cross-section, First order linear Partial Differential equations.
Classification: 16.8.

Nature of problem:
The program simultaneously computes momentum transfer matrix elements and excitation and charge transfer probabilities for collisions between protons and hydrogen atoms in the second quantum levels in any of the three molecular states associated with the second quantum level of the hydrogen atom. The alternative procedure using direct numerical integration is also discussed and developed.

Solution method:
The exchange matrix elements are evaluated by solving a set of coupled differential equations suggested by Cheshire. The differential equations relating the transition amplitudes are combined with the differential equations relating the matrix elements, and are solved by the Adams-Moulton method.

Running time:
The time required to compute the probability for a given energy and impact parameter depends upon the energy, and increases rapidly as the energy is decreased. For example, for an energy of 10 KeV, the time is 300 seconds for any impact parameter but for an energy of 500 eV, it is 1800 seconds.