FINDSYM

Version History

Sep 2021, version 7.1.3 (1) Improved the handling of tolerances. (2) Made several error messages easier to understand. (3) Added a command-line tool called findsym_p1reduction, which reduces the symmetry of the incoming structure to P1 in the same unit cell, and delivers the output in CIF format. (4) Now reads magnetic moments which are represented in spherical (xcart||a, zcart||c*) rather than crystal-axis components, meaning that the item on the _atom_site_moment.* category is spherical_modulus, spherical_azimuthal, and spherical_polar rather than crystalaxis_x, crystalaxis_y, and crystalaxis_z. If the moments are provided in both coordinate systems, only the crystal-axis coordinates will be read. (5) Fixed minor bugs.

Jun 2021, version 7.1.2. Changed the way that incommensurate k vectors are represented internally; this extensive revision should be invisible to users.

Jan 2021, version 7.1.1. The subroutine that reads CIF input now accepts both "+1" or "1" for the magnetic component of a symmetry operation.

Jul 2020, version 7.1. (1) The implementation of symmetry detection for modulated structures (superspace groups and magnetic superspace groups) was completed. This was a major effort. Note that this incommensurate structures cannot be processed if the "show data in a form" box is checked; they only work in pass-through mode. (2) Tolerances for Fourier modulation coefficients were implemented, and new CIF tags were created for specifying these new tolerances (_iso_accmoddisp, _iso_accmodocc, _iso_accmodmag, _iso_accmodrot). Very large tolerances on the modulation coefficients have not yet been protected against. (3) The symmetry detection algorithm was substantially modified to better handle large tolerances without crashing. (4) A weakness has now been corrected, so that the final symmetry group always includes every symmetry element present in the input file, in addition to any other symmetry elements detected. This improvement does not apply if the "show data in a form" box is checked, but only applies in pass-through mode. (5) The output page now presents maximum and rms-average shifts in atomic position, occupancy, magnetic moment, and rotational moment for each unique Wyckoff site of the detected high-symmetry structure. These are the shifts required to raise the symmetry of the input structure to the level detected. (6) The output page now includes a button for downloading a CIF file containing the detected high-symmetry structure. (7) The output page now includes all non-zero tolerances specified by the user that are relevant to the input structure. (8) The allowed length of an atom-type symbol was uniformly extended from 2 to 6 characters in all subroutines. (9) Other bug fixes and enhancements.

Oct 2019, version 7.0. Support added for the detection of superspace-group symmetry (magnetic or non-magnetic) for modulated structures (excluding composite structures). This feature is only partially implemented at present, but will be extended.

May 2019, version 6.1. (1) cell volume added to CIF output, (2) significantly improved ability to function with large displacive tolerances, (3) preparation for future CIF-output features.

Feb 2018, version 6.0. (1) Occupational and rotational order parameters have now been implemented in FINDSYM. (2) The web version now has a "show data in a form" checkbox in the Import Data section, so that the form page (manual structure entry) is bypassed by default. (3) In the command line version of FINDSYM, the format of the input file has been fundamentally changed to use key words (see findsym.txt in the distribution for details), which will make back compatibility of future versions easier to achieve; and rather than piping this input file into FINDSYM, send the filename as an argument to FINDSYM. This version is back compatible with earlier versions,i.e., FINDSYM still accepts the input file in the old format.

Nov 2017, version 5.1.1. Minor bug fixes.

Aug 2017, version 5.1.0. (1) Fundamental algorithm and efficiency improvements, particularly for cases involving large numbers of atoms and for cases involving substantial "noise" in the atomic coordinates. (2) Errors encountered at large tolerance values have been resolved. When a large tolerance is requested, that tolerance is now reset to 1/3 the smallest same-atom-type nearest-neighbor distance for each atom type. These changes also propagated to ISOCIF.

Jan 2017, version 5.0.1. Minor bug fixes.

Dec 2016, version 5.0.0. (1) A series of internal improvements to the symmetry-detection routine. (2) Separate tolerances for cell parameters, atomic positions, and magnetic moments. (3) Any atoms in the "Type of each atom in the unit cell" list that have negative coefficients are ignored by the symmetry-detection routine. (4) Higher precision for the cell-parameters in CIF output. (5) Now accepts uppercase X,Y,Z symbols in space-group operators from CIF input. (6) Minor bug fixes. (7) A new command-line interface has been developed, but only for the Linux OS. The findsym_cifinput preprocessor accepts a CIF-input filename and produces output that can be piped to findsym, so that the final output is a CIF containing the new higher-symmetry CIF. (8) For the command-line version, the CIF tags _iso_acclat, _iso_accpos, _iso_accocc, and _iso_accmag have been implemented to assign lattice-parameter, atomic-position, site-occupancy, and magnetic-moment tolerances. (9) For the command-line version, the CIF tag _iso_ignore_atom has been implemented to allow the user to ignore ("y" or "Y") or keep (".") any atom in the _atom_site loop. (10) For either the we interface or command-line interface, if the CIF input employs "_iso_expected_sg " to indicate an expected space group, the CIF output will indicate a warning if the expected space groups is not realized. And if CIF input employs "_iso_expected_volrat " to indicate an expected ratio of old/new primitive cell volume, the CIF output will indicate a warning if the expected volume ratio is not realized. This feature was added to facilitate tests.

Dec 2015, version 4.3.1. Fixed a problem which occurs when a large tolerance is used.

Oct 2015, version 4.3. Fixed symmetry-detection problems that affected less-common cases, and improved code efficiency when dealing with large low-symmetry input.

June 2014, version 4.2. Allowed data to be imported from a CIF file and fixed some minor bugs.

May 2013, version 4.1. Added feature: atom types can be entered using multipliers (eg. 2*Mg for Mg Mg)

March 2013, fixed bug that sometimes displayed incorrect magnetic moments in output.

January 2013, added magnetic moments of atoms for identification of magnetic space group symmetries. Also allowed chemical symbols instead of integers for designating the types of atoms.

May 2012, added applet from ISOCIF for viewing structure

April 2006, version 3.2.1. Fixed bug for R-centered lattices.

July 2005, version 3.2. Added monoclinic and orthorhomic settings.

November 2004, version 3.1. Added option to use different settings for space groups.

November 2004, version 3.0. Fixed how tolerance is handled. Added a centering option for basis vectors of the unit cell. Removed unnecesary data from output. Inserted more user-friendly error messages.

November 2003, version 2.6. Added graphical rendition of the unit cell (internet version only).

August 2000, version 2.3.3. Fixed another bug relating to the identification of the Wyckoff positions and the origin.

July 2000, version 2.3. Fixed another bug relating to the identification of the Wyckoff positions.

June 2000, version 2.2. Fixed a bug relating to the identification of the Wyckoff positions.

May 2000, version 2.0. This program now works for any arbitrary orientation of axes.

August 1999. version 1.2. Fixed bug in origin of space group. Also changed setting to Origin Choice 2 so that it would match the default setting in ISOTROPY.

January 1999, version 1.1.1. Made some minor changes.

June 1998, version 1.1. Fixed a bug.

April 1998, version 1.0-2. Fixed some bugs.

January 1998, version 1.0. First version made available at this internet site.