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成龙1999

铁杆木虫 (职业作家)

[交流] 请教

'Acta Crystallographica, Section E'编辑提出问题:

Please complete.
_vrf_PLAT_089_I  
;
PROBLEM :  Poor Data/Parameter Ratio (Zmax. LT. 18)....7.85
RESPONSE :   ?????

如何回答?
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zhousm

木虫 (正式写手)

数据参数比偏低(一般要>10)。这个不好整。
2楼2009-10-16 21:10:37
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xi2004

至尊木虫 (职业作家)

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成龙1999(金币+5,VIP+0):很有参考价值,谢谢 10-17 07:56
提示: 以 Poor Data/Parameter Ratio Response google一下, 看看人家怎么response的

举例如下:

Acta Cryst. (2009). E65, m461  [ doi:10.1107/S1600536809011039 ]

http://journals.iucr.org/e/issue ... hg2490checkcif.html


N-(2-Ferrocenylethylidene)-4-(trifluoromethyl)aniline
W. Imhof
Online 28 March 2009


PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .......       0.94      
Author Response: The crystal was rather small and there was just no significant intensity at angles >23.29 deg.  

PLAT242_ALERT_2_A Check Low       Ueq as Compared to Neighbors for         C8     
Author Response: C8 is the carbon atom of a highly disordered CF3 group which causes the high thermal parameters of fluorine atoms and the comparatively low thermal parameters at C8. It was not possible to determine more than the reported two positions for each fluorine atom. The situation is also not improved if the fluorine atoms are refined isotropically.  

--------------------------------------------------------------------------------
Alert level B
THETM01_ALERT_3_B  The value of sine(theta_max)/wavelength is less than 0.575
            Calculated sin(theta_max)/wavelength =    0.5563
Author Response: The crystal was rather small and there was just no significant intensity at angles >23.29 deg.  

PLAT023_ALERT_3_B Resolution (too) Low [sin(theta)/Lambda < 0.6]..      23.29 Deg.
Author Response: The crystal was rather small and there was just no significant intensity at angles >23.29 deg.  

PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        F3X     
Author Response: C8 is the carbon atom of a highly disordered CF3 group which causes the high thermal parameters of fluorine atoms and the comparatively low thermal parameters at C8. It was not possible to determine more than the reported two positions for each fluorine atom. The situation is also not improved if the fluorine atoms are refined isotropically.  

--------------------------------------------------------------------------------
Alert level C
            Value of measurement temperature given =   183.000
            Value of melting point given =     0.000
GOODF01_ALERT_2_C  The least squares goodness of fit parameter lies
            outside the range 0.80 <> 2.00
            Goodness of fit given =      0.785
REFLT03_ALERT_3_C  Reflection count < 95% complete
           From the CIF: _diffrn_reflns_theta_max           23.29
           From the CIF: _diffrn_reflns_theta_full          23.29
           From the CIF: _reflns_number_total               2064
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         2205
           Completeness (_total/calc)             93.61%
Author Response: The crystal was rather small and there was just no significant intensity at angles >23.29 deg.  

REFNR01_ALERT_3_C  Ratio of reflections to parameters is < 10 for a
            centrosymmetric structure
            sine(theta)/lambda                0.5563
            Proportion of unique data used    1.0000
            Ratio reflections to parameters   8.7458
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.94      
Author Response: The crystal was rather small and there was just no significant intensity at angles >23.29 deg.  

PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       8.75      
Author Response: Due to the small size of the crystal intensities at higher angles were extremely low. In addition, the anisotropic refinement of the disordered CF3 group leads to more refined parameters. If these fluorine atoms are refined isotropically, data/parameter ratio of course improves, but R values increase significantly.  

PLAT213_ALERT_2_C Atom F2X     has ADP max/min Ratio .............       3.40 prola
Author Response: F2X is part of a highly disordered CF3 substituent. It was not possible to determine more than the reported two positions for each fluorine atom. The situation is also not improved if the fluorine atoms are refined isotropically.  

PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
--------------------------------------------------------------------------------
Alert level G
PLAT301_ALERT_3_G Note Main Residue  Disorder ....................      12.00 Perc.
PLAT779_ALERT_4_G Suspect or Irrelevant (Bond) Angle in CIF ......      22.10 Deg.
              F1X  -C8   -F1      1.555   1.555   1.555                        
PLAT779_ALERT_4_G Suspect or Irrelevant (Bond) Angle in CIF ......      31.80 Deg.
              F2X  -C8   -F2      1.555   1.555   1.555                        
PLAT779_ALERT_4_G Suspect or Irrelevant (Bond) Angle in CIF ......      38.20 Deg.
              F3X  -C8   -F3      1.555   1.555   1.555
xi2004-emuch@163.com
3楼2009-10-16 23:20:42
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