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Manuscript Title: A Fortran program to simulate quadrupole-distorted NMR powder patterns.
Authors: E.D. von Meerwall
Program title: HEQSIM2
Catalogue identifier: ABMW_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 13(1977)107
Programming language: Fortran.
Computer: IBM 370/158.
Operating system: OS/MVT, OS/VS2.
RAM: 25K words
Word size: 32
Peripherals: graph plotter.
Keywords: Powder pattern, Quadrupole distortion, Absorption, Solid state physics, Resonance magnetic, Line shape, Dipolar broadening, Dispersion, Experiment, Spectrum, Simulation, Chemical shift, Derivative.
Classification: 7.4.

Nature of problem:
The effects of a quadrupole interaction, dipolar broadening, and a chemical shift on the NMR spectrum (static) of a nucleus of arbitrary spin where i is between 1 and 5, are simulated and plotted.

Solution method:
Perturbation results are used to produce satellite powder patterns and central transition (m=1/2 to -1/2) in second order quadrupolar theory, and anisotropic chemical shift in first order. The Kramers-Kronig relations are used to transform absorption to dispersion mode, and gaussian or lorentzian convolution functions simulate dipolar broadening. Histrographic techniques are used for the central transition. Inhomogeneities in the quadrupolar interaction are simulated by adding discrete component spectra.

Restrictions:
Within the limitations of the program, no extensions are appropriate.

Unusual features:
To maximize the utility and flexibility of the program, the following features are provided:
(1) most aspects of the simulations are self-scaling with optional enlargement factors;
(2) up to five Nu Q-values per simulation provide inhomogeneity; five simulations with different eta are produced per case, with derivatives; absorption or dispersion mode may be selected; lorentzian or gaussian dipolar broadening may be of different size for central transition and satellites;
(3) full chemical shift (3 components) is simulated; shift effects should be smaller than quadrupole effects; and
(4) a plot of resonance derivative vs. field, scalable for direct comparsion with experiment, is optional, and consists of the components of different asymmetry.

Running time:
On the IBM 370/158, execution per case ranges from about 15 sec for I=1 or 3/2 and low, homogeneous quadrupole interaction to over 4 min for inhomogeneous anisotropic cases of high quadrupole interaction per dipolar broadening, and dispersion mode. Compilation (FORTRAN G compiler) takes about 16 CPU sec.