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)