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Manuscript Title: Initial values of parameters for variable moment of inertia models.
Authors: G.S. Anagnostatos, K. Demakos, A. Vassiliou
Program title: INVAP
Catalogue identifier: ABQN_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 24(1981)197
Programming language: Fortran.
Computer: CDC 3300.
Operating system: MASTER 4.1.
RAM: 20K words
Word size: 24
Keywords: Nuclear physics, Rotational spectra, Collective models, Variable moment-of Inertia models, Fitting.
Classification: 17.20.

Nature of problem:
The long write-up summarizes the procedure for determining the initial values of parameters for the fitting of rotational spectra in even-even nuclei. The functional form of the fitting is: EI=C2J0)**2 + C3(Ji- (Ji-J0)**3 + C4(Ji-J0)**4 + ... with the condition delta EI/delta JI = 0, where EI and JI are the excitation energy and moment of inertia at a certain angular momentum I, respectively, and Ci and J0 are the parameters of interest. While the determination of these parameters can be done following several standard fitting procedures, in all cases (since we always have to solve a non-linear system of equations), there is a great sensitivity to the initial values of these parameters. The purpose of this paper is to determine initial values suitable for any standard fitting procedure, by using an approximate solution of the problem.