**
PROGRAM SUMMARY
**
**
Title of program:
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IPA, SCHROED
**
Catalogue identifier:
**
ADLV
**
Ref. in CPC:
**
128(2000)622
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Distribution format: ** zip file
**
Operating system: ** MS DOS
**
Peripherals Required: ** disc
**
Number of lines in distributed program, including test data, etc:
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11581
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Programming language used: ** Fortran
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Computer: ** IBM PC, Pentium 90

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Nature of physical problem:
**

This program constructs an accurate potential curve of a 1Sigma or a
1Pi state of a diatomic molecule from given energy levels of the state
observed experimentally.

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Method of solution
**

The radial Schrodinger equation is solved with an approximate potential
and zeroth-order eigenvalues and wave functions are obtained. In the
next step, using the first order perturbation theory we seek a
correction to the approximate potential that minimizes the difference
between the observed and the corrected energy levels.

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Restrictions on the complexity of the program
**

The approximate potential U0(R) and the correction to it deltaU(R) are
defined in numerical form as arrays of points. Points of deltaU(R) must
be equidistant in R. The addition of U0(R) and deltaU(R) is performed
by the user.

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Typical running time
**

The running time depends on the total number of energy levels and the
number of points of deltaU(R). Fitting of a potential in a typical case
(1000 levels, 20 points) requires several minutes.