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_053 Test for specification xtal_dimension_min
_054 Test for specification xtal_dimension_mid
_055 Test for specification xtal_dimension_max
_056 Test for specification xtal_radius
_057 Test for absorption correction needed
_058 Test for Tmax specified
_059 Test for Tmin specified
_060 RR Test
_061 RR' Test
_062 Rescale Tmin & Tmax
_063 Test crystal size
Alert for crystals with at least one dimension probably too large for the
homogeneous part of the Xray beam when used for data collection using
crystal monochromated radiation. An exception will be datacollection using
a beta-filter and a sufficiently large collimator.
_064 Test for T(max) .GE. T(min)
_065 Test for applicability of (semi-)empirical abs.corr.
_070 Test for duplicate atom labels
_071 Uninterpretable label
This alert relates to unintelligable labels on input and are deleted from
the model & checking.
_080 Test maximum shift/error
_081 Test for maximum shift/error given
_082 Test for reasonable R1 value
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_084 Test for reasonable R2 value
R2 will in general have a value twice of that of R1 with refinement on
F**2. Significantly larger values usually indicate a poor refinement model.
_086, _087 Test for reasonable S value
S should in general be close to 1 at the end of a refinement with a proper
weighting scheme. If not, there might be significant unresolved problems
with the model.
_088 Test for reasonable Data / parameter ratio (centro)
_089 Test for reasonable Data / parameter ratio (non-centrosymmetric)
_095 Test for residual density maximum given
_096 Test for residual density maximum given
_097 Test maximum residual density
_098 Test for minimum residual density
_099 Test for minimum residual density less zero
_11x : ADDSYM Tests for missed symmetry (with an expanded MISSYM (C) clone)
These tests warn for missed or possible higher (pseudo) symmetry in the
structural model (i.e. based on the coordinate data). Close examination of
the situation at hand is indicated in order to prove/disprove the issue
(usually in combination with the reflection data).
The tests are split-up in three classes of problems:
_110 Reports on potential (pseudo/real) lattice centering or cell halving.
_111 Reports on potential additional (pseudo/real) inversion centres.
_112 Reports on potential additional (pseudo/real) rotation axes and
mirrors.
_113 Report New spacegroup suggested by ADDSYM
Note: Disordered atoms are not taken into account in the tests.
_12x : Tests for consistency and completeness of symmetry data items in
CIF.
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Symmetry in the CIF should be provided in the CIF both explicitly with a
_symmetry_equiv_pos_as_xyz loop and implicitly with
_symmetry_space_group_name_H-M.
The tests done include (with some redundancy to point to the real problem)
_120 Test for consistency of the _symmetry_equiv_pos_as_xyz set with
symmetry_space_group_name_H-M.
_121 Test for valid symmetry_space_group_name_H-M symbol.
_122 Test for missing (i.e. ?) symmetry_space_group_name_H-M symbol.
_123 Test for uninterpretable or inconsistent Spacegroup information.
_124 Test for uninterpretable or absent explicit symmetry records.
_130 - _140 : Test for symmetry restrictions on cell-parameters.
Symmetry restrictions on cell dimensions are checked.
_141 - _146 : Test Su's on cell parameters
The presence of su's (where required) and value are checked. Su's as given
by the diffractometer software are often much smaller than realistic.
_150 Check Reported versus Calculated volume
An alert is issued when the reported unit cell volume differs significantly
from the volume calculated on the basis of the supplied cell dimensions.
_16x : Tests for missing s.u. on coordinates or refined C-H
Positional parameters for all non-hydrogen atoms in general positions are
checked for the presence of a non-zero s.u. on them. This includes
parameters fixed to fix the origin in polar space groups which is no longer
necessary when refinement is done with modern programs (e.g. SHELXL, XTAL).
_161 Missing or Zero su (esd) on x-coordinate.
_162 Missing or Zero su (esd) on x-coordinate.
_163 Missing or Zero su (esd) on x-coordinate.
_164 Refined C-H H-atoms in heavy-atom structure (warning)
Such H-atoms are better refined at calculated positions riding on the atoms
they are attached to.
_201 Test for isotropic non-hydrogen atoms in main residue (molecule)
This test reports on non-hydrogen atoms that were refined with isotropic
displacement parameters only in the main residue. Such a practice is
unusual by modern standards and only needed for minor disorder modelling.
_202 Test for isotropic non-hydrogen atoms in anion/solvent (small moiety)
This test reports on isotropically refined atoms in small moieties (usually
anions or solvent)
_211 Test for NPD ADP's in main residue(s)
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36
This test reports on non-positive definite (i.e. complex and unrealistic)
anisotropic displacement parameters in the main residue.
_212 Test for NPD ADP's in small moieties (solvent/anions)
This test reports on non-positive definite (i.e. complex and unrealistic)
anisotropic displacement parameters in small moieties (solvent/anion).
_213 ADP maximum/minimum ratio test for main residue
The maximum and minimum main axis ADP ratio (Angstrom Units) is tested for
the main residue. Large values may indicate unresolved disorder.
_214 ADP maximum/minimum ratio test for small moiety
The maximum and minimum main axis ADP ratio (Angstrom Units) is tested for
the minor residue(s). Large values may indicate unresolved disorder.
_220 Test Ueq(max)/Ueq(Min) range for non-H in main residue(s)
This test reports on a larger than usual U(eq) range for the non-hydrogen
atoms. Too high or too low Ueq's may be an indication for falsely
identified atomic species (i.e. Br versus Ag)
_221 Test Ueq(max)/Ueq(Min) range for non-H atoms in minor residue(s)
This test reports on a larger than usual U(eq) range for the non-hydrogen
atoms. Too high or too low Ueq's may be an indication for falsely
identified atomic species (i.e. Br versus Ag)
_222 Test Ueq(max)/Ueq(Min) range for H atoms in main residue(s)
This test reports on large ranges in displacement parameters for hydrogen
atoms.
_223 Test Ueq(max)/Ueq(Min) range for H atoms in minor residues(s)
This test reports on large ranges in displacement parameters for hydrogen
atoms.
_230, _233 : Hirshfeld rigid bond test
Components of anisotropic displacement parameters along chemical bonds are
assumed to be equal in magnitude. Large differences supposedly indicate
contamination of these parameters with other (unresolved) effects such as
disorder and/or overrefinement. Atom sites assigned the wrong scattering
type (e.g. Ag versus Br) should generate 'problem signals' with this test.
Data sets corrected for absorption effects with DELREF techniques (e.g.
DIFABS, SHELXA, XABS2) often show large DELU values for bonds involving the
heaviest atom.
_241, _242 Test for too high/low U(eq) as compaired to neighbours
The U(eq) value of an atom is compaired with the average U(eq) for to non-
hydrogen atoms bonded to it. Large differences may indicate that the wrong
atom type was assigned (e.g. N instead of O).
_301, _302 : Detection of Disorder
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