NESC0632 MMM3
MMM-3, Semi Rigid Molecule Normal Modes and Frequencies for Slow Neutron Scattering Calculation
NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES
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| Program name | Package id | Status | Status date |
|---|---|---|---|
| MMM-3 | NESC0632/01 | Tested | 01-DEC-1975 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NESC0632/01 | IBM 370 series | IBM 370 series |
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3. DESCRIPTION OF PROBLEM OR FUNCTION
MMM3 computes the eigenvalues
(frequencies) and eigenvectors (normal modes) for a semi-rigid
molecule, and computes the transformation matrix for expressing
the Cartesian displacements of the atoms in terms of the normal
coordinates. Computation of the effective atomic masses and mean-
squared amplitudes of vibration for use in slow neutron scattering
calculations is included as well.
MMM3 computes the eigenvalues
(frequencies) and eigenvectors (normal modes) for a semi-rigid
molecule, and computes the transformation matrix for expressing
the Cartesian displacements of the atoms in terms of the normal
coordinates. Computation of the effective atomic masses and mean-
squared amplitudes of vibration for use in slow neutron scattering
calculations is included as well.
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4. METHOD OF SOLUTION
The procedure centers around the manipulation
of matrices: 1) the force constant matrix, 2) the transformation
matrix which describes changes in bond angles and distances, and
3) the new coordinate matrix. In formulating a problem for
solution, the group vibration method is used, i.e. a molecule is
divided into groups of atoms with each atom in one and only one
group, and the motion of each atom is described as the sum of
displacements within a group (intragroup motions), together with
translational and rotational motions of the groups considered as
rigid units (skeletal motions).
The procedure centers around the manipulation
of matrices: 1) the force constant matrix, 2) the transformation
matrix which describes changes in bond angles and distances, and
3) the new coordinate matrix. In formulating a problem for
solution, the group vibration method is used, i.e. a molecule is
divided into groups of atoms with each atom in one and only one
group, and the motion of each atom is described as the sum of
displacements within a group (intragroup motions), together with
translational and rotational motions of the groups considered as
rigid units (skeletal motions).
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NESC0632/01, included references:
- D. H. Speas:Matrix Routine for Calculating Normal Modes, Frequencies, and
Atom Displacements in Molecules, Aerojet
Nuclear Company Program Description No. P00320, August 1964.
- H. L. McMurry:
A Simplified Group Vibration Method for Calculating Normal Vibrations
of Large Molecules,
Spectrochimica Acta, Vol. 21, pp. 2091-2103, 1965.
- H. L. McMurry and D. Speas:
Vibrational Analysis of Propane and Its Symmetrical Deuterium
Substituted Isomers,
Spectrochimica Acta, Vol. 21, pp. 2105-2117, 1965.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
If a
degeneracy exists, the eigenvalues are calculated correctly, but
the eigenvectors may be wrong unless special precautions are
employed in formulating the problem. The procedure to be followed
in such cases is given in the program instructions.
If a
degeneracy exists, the eigenvalues are calculated correctly, but
the eigenvectors may be wrong unless special precautions are
employed in formulating the problem. The procedure to be followed
in such cases is given in the program instructions.
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NESC0632/01
| File name | File description | Records |
|---|---|---|
| NESC0632_01.001 | SOURCE PROGRAM | 527 |
| NESC0632_01.002 | SAMPLE PROBLEM DATA | 258 |
| NESC0632_01.003 | SAMPLE PROBLEM PRINTED OUTPUT | 829 |
Keywords: eigenvalues, eigenvectors, lattice vibrations, molecules, scattering.