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Manuscript Title: I. A computer program for generation of a complete set of coordinates and force matrices for normal mode calculations of crystals and molecules.
Authors: F.Y. Hansen
Program title: FYCOOR
Catalogue identifier: ACXQ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 14(1978)193
Programming language: Fortran.
Computer: IBM 370/165.
Operating system: OS/MVT RELEASE 21.7.
RAM: 485K words
Word size: 32
Peripherals: disc.
Keywords: Solid state physics, Crystal structure, Neutron, Normal mode, Coordinate, Force constant, Group theory, Molecule, Scattering.
Classification: 7.6, 7.8.

Subprograms used:
Cat Id Title Reference
ACXR_v1_0 FYFRE CPC 14(1978)219
ACXS_v1_0 FYADJ CPC 14(1978)245

Revision history:
Type Tit le Reference
correction 000ACORRECTION 28/11/77 See below

Nature of problem:
In this paper a computer code, FYCOOR, is described for generation of a complete set of coordinates to be used in a normal mode calculation for crystals or for molecules. This program eliminates or reduces time- consuming and error producing complexities, which have handicapped the application of some computer programs for calculating normal modes.

Solution method:
Group theory is used in the program in such a way, that many (often most) of the coordinates used for the potential energy are generated from a minimum input of "basis-set coordinates", which may be arbitrary. All force constant matrices are set up by the program with very small "dummy" force constants that are easily updated in a selective manner by the user to give the desired potential. The program includes a logic, which assures that force constants, which are interrelated by symmetry are correctly displayed and used, and there are provisions, which check if the potential is invariant against pure rotations and translations.

Restrictions:
In the present version 20 input coordinates, 10 atoms per unit cell or per molecule, 10 interaction types and 48 symmetry operations (which are the maximum number of operations to occur) may be considered. Detailed information on how to alter the present dimensions may be found in the long write-up.

Running time:
The running time depends on the problem. In the case of diamond, where the number of symmetry operations is 48, the running time for 2 input coordinates with 4 interaction types was 120 s. In the case of selenium, where the number of symmetry operations is 6, the running time for 3 input coordinates with two interaction types was 20.6 s, and for 9 input coordinates with one interaction type it was 33.6 s. The compilation time of 12.2 s is included in these times.

CORRECTION SUMMARY
Manuscript Title: Unpublished correction to I. A computer program for generation of a complete set of coordinates and force matrices for normal mode calculations of crystals and molecules.
Authors: F.Y. Hansen
Program title: 000ACORRECTION 28/11/77
Catalogue identifier: ACXQ_v1_0
Distribution format: gz
Classification: 7.6, 7.8.