EMGBO

Program: EMGBO

This program generates a text file that contains a histogram of misorientation angles for either a set of random octonions (pairs of quaternions) of for a fixed CSL boundary with the second boundary random. The underlying theory can be found in the following paper: T. Francis, I. Chesser, S. Singh, E.A. Holm and M. De Graef. "A New Octonion Metric for Grain Boundary Interpolations". Acta Materialia, 166:135-147 (2019) DOI. This program was used to generate the misorientation plots in Figs. 2 and 3 of this paper.

The program uses a template file in the usual way:

EMGBO -t

and its content is as follows:

&GBOlist
! point group number
 pgnum = 32,
! number of samples to compute
 numsamples = 100000,
! number of histogram bins
 numbins = 180,
! number of threads for parallel computation
 nthreads = 1,
! CSLtype
 CSLtype = '',
! fix A/B boundary ?
 fixedAB = .FALSE.,
! output will be stored in this text file (EMsoft relative pathname)
 outname = 'undefined'

If the CSLtype variable is left undefined, then the program will generate pairs of random octonions. If CSLtype is set to a CSL identifier (e.g., 3 or 19a), then the program will keep one octonion fixed to this grain boundary, and randomly vary the other octonion. If fixedAB is set to .TRUE., then the program will only use symmetry operators on the second octonion; when set to .FALSE., the symmetrical equivalents of both octonions will be generated to determine the misorientation angle. The plots in the figure cited above will serve as examples for the output of this program (a text file that can be read into a spread sheet program to generate the histograms).