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xner

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[交流] 【求助】几个B类和C类错误

CIF在线检测出现几个错误，帮忙给改下呢，金币不多，希望大家帮帮忙啊！CIF在线检测PDF文件已上传。http://d.namipan.com/d/2c9058fdf ... c0e7643eb76e0460100
B类错误：
PLAT250

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PLAT250 Type_2 Test for unusual anisotropic average UIJ
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An average value of the U(i,j) tensor of the asymmetric unit of a residue
is calculated. An ALERT is generated when the corresponding U3/U1 ratio
deviates significantly from 1.0. Large values of this ratio should be taken
as an indication of possible systematic errors in the data or errors in
the model. Visual inspection of an ORTEP plot will show that many
displacement ellipsoids have their major axis pointing in the same direction.

几个C类错误：
Alert1C
PROC-NAME: ABSTY02 Type_1

PURPOSE: To check that _exptl_absorpt_correction_type contains some reference text.

PROCEDURE:
TEST

IF _exptl_absorpt_correction_type !~ 'Ref:'
OR _exptl_absorpt_process_details is missing
issue ALERT C
"Alert C An _exptl_absorpt_correction_type has been given without a literature citation. This should be contained in the _exptl_absorpt_process_details field."
A literature citation to the absorption correction method must be provided. However, do not append this to the keyword given with _exptl_absorpt_correction_type. There is a separate data name entry for the citation which is _exptl_absorpt_process_details. The citation should be in parentheses in the usual citation format.
Example:
_exptl_absorpt_correction_type psi-scan
_exptl_absorpt_process_details '(North et al., 1968)'

ALERT2C
PLAT220 Type_2 Test Ueq(max)/Ueq(Min) range for non-H atoms in non-solvent
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This test reports on a larger than usual U(eq) range for the specified
element type in the non-solvent/anion part of the structure.
Too high or too low Ueq's may be an indication for incorrectly
identified atomic species (i.e. O versus N).

PLAT366 Type_2 Test for short C? - C? (Angstrom Difference) XRAY: 1.50
--------------------------------------------------------------------------------

Large deviations from generally accepted values may indicate model problems,
over refinement etc. Default C?-C? = 1.50 Ang. (X-Ray) value from
Ladd & Palmer, Structure Determination by Xray Crystallography (1985).
This ALERT may also arise when the hybridisation at least one atom is
not recognized.

PLAT601 Type_2 Test for (Unreported) solvent accessible voids
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Crystal structures in general do not contain large solvent accessible voids
in the lattice. Most structures lose their long-range ordering when solvent
molecules leave the crystal. Only when the remaining network is strongly
bonded (e.g. zeolites and some hydrogen bonded networks) the crystal
structure may survive.
Residual voids in a structure may indicate the omission of (disordered)
density from the model. Disordered density may go undetected when smeared
since peak search programs are not designed to locate maxima on density
ridges. The presence or absence of residual density in the void may be
verified on a printed/plotted difference Fourier map or with PLATON/SQUEEZE.
Voids of 40 Ang**3 may accommodate H2O. Small molecules such as
Tetrahydrofuran have typical volumes in the 100 to 200 Ang**3 range.
This test reports the volume of the largest solvent accessible void in the
structure.
A paper reporting a crystal structure with a significant solvent accessible
void should at the least discuss the issue.

PLAT244 Type_4 Test for unusually low solvent U(eq) as compared with bonded neighbors
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The U(eq) value of an atom in the solvent or ion is compared with the average
U(eq) for non-hydrogen atoms bonded to it. Large differences may indicate
that the wrong atom type was assigned (e.g. N instead of O). False alarms may
occur for terminal groups such as the t-butyl moiety.

[ Last edited by xner on 2010-9-27 at 11:38 ]

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