configuration

Structure of .CFG file

General notes

text lines that describe configuration of ParaCell
all lines are in the following format
keyword=number or keyword1=keyword2
(almost all parameters are optional)

for some methods combinations (those can not physically exist) are skipped
for ortorhombic system a>=b>=c,
for monoclinic system a>=c,
for triclinic system a>=b>=c.

Common parameters

NON_INDEXED=X the maximal number of unindexed reflections, NON_INDEXED = input reflections - LIMIT

LIMIT=X the minimal number of indexed reflections to be accepted (default value is the number of input reflections), LIMIT = input reflections - NON_INDEXED

RATIO = X at least X of reflections must be indexed. In other words, X is the minimal ratio of indexed reflections to input reflections.

INPUT_ERR=X the maximal assumed error of input reflections (in 2Th = degrees)
a correct indexed reflection must be in [input 2Th-INPUT_ERR/2,input 2Th+INPUT_ERR/2]
default value is 0
if set, it overrides FWHM settings!!!

NUMBER=X the number of assumed hkl triples, first lines from the .hkl input file (not used for TREOR-based method)
default value = min(1000, 20 * input reflections)

OPTIMIZE = X after the execution of the indexing method, try to optimize (i.e., increase F20) X best results.

SYSTEM=X choice of a crystal system, the following numbers are supported:

• 1=cubic,
• 2=hexagonal,
• 3=tetragonal,
• 4=orthorhombic,
• 5=monoclinic,
• 6=triclinic.

MAX_A, MAX_B, MAX_C , MAX_ANGLE, MAX_BETA , MAX_V or MIN_A, MIN_B, MIN_C, MIN_ANGLE , MIN_BETA, MIN_V Limits for lattice parameters or cell volume.
If they are not specified, default values are used: a,b,c in [3,25], angles in [60,120] degrees.
Note: MAX_ALPHA, MAX_GAMMA, MIN_ALPHA, MIN_GAMMA options were deprecated, use MAXIM_ANGLE or MINIM_ANGLE option instead

DB_BEST_LIST=X how many best solution will be printed (default value is 100)

DB_DETAIL_LIST=X how many best solution (in detail) will be printed (default value is 10)

Methods for solution

the following methods (or variants) can be selected by parameter METHOD :

• MGLS = a new experimental multigrid local search method (from version 1.2), special options for [mgls-based] method
• TREOR = TREOR method, special options for [treor-based] method
• DICHOTOMY = DICHOTOMY method (from version 0.99), special options for [dich-based] method
• grid-based method, special options for [grid-based] method, there are 3 grid-based methods:
  • GRID1 = systematic search in direct lattice parameters (equidistant step, arithmetic sequence)
  • GRID2 = systematic search in direct lattice parameters (geometric sequence)
  • GRID3 = systematic search in reciprocal lattice parameters (limits are derived from input, geometric sequence)

Device for computation

For CPU computation use "device=CPU" and setup the number of threads by keyword THREADS
Otherwise, the GPU (CUDA) is used (but this is available only for CUDA version)

Experimental options

ZERO_SHIFT=X turn on a zero-shift correction, maximal assumed value of shift is X

IMPROVE_CELL=1 turn on a cell parameters optimization, not implemented now. use option OPTIMIZE instead

STOP_FM20=X if a unit cell with FM20>=X is found, computation immediately stops

GPU computation

available from version 0.9, only CUDA CC 2.0 (Fermi generation) and better can be used
Note If this error "the launch timed out and was terminated in" is displayed, you can correct it in Windows OS by following approaches first second

Limits of the current implementation

• input file can contain at most 64 reflections
• zero-shift correction is just experimantal, so computed values of M20 or F20 are lower than optimal,
• Estimation of remaining time is missing or inexact (available for GPU and GRID1)

TODO

• volume check in TREOR method
• correct parameters for improve_cell
• optimize GPU execution (execution configuration)