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[交流] 请教几个C类错误

PLAT340 ：Type_3 Check Bond Precision for C-C in Light Atom Structures (Z(max) < 20) 。
The average su for X-Y bonds is tested (named bond-precision). X-Y will generally be C-C bonds, unless there are none. In the last case the su's of the lowest element numbers are considered (excluding hydrogen). There are three test ranges: one for structures with the largest element Z < 20, one for the largest Z in the range 20 to 39 and one for structures with Z(max) 40 or higher (_340, _341 and _342 respectively)。

PLAT152 ：Type_1 Check for consistency of su on Volume and cell parameters。
Some software packages calculate Volume su's incorrectly. The correct formula(based on the propagation of error expression) may be found in: M. Nardelli, Computer & Chemistry, (1983), 7, 95-98.or  C. Giacovazzo ed. in 'Fundamentals of Crystallography', Second Edition, Oxford University Press, 2003,  p135.

PLAT066： Type_1 Test whether Predicted and Reported Transmission Ranges are Identical 。
The predicted and reported transmission ranges are found to be identical which is not to be expected. CIF's generated with SHELXL97 report transmission ranges based on the crystal dimensions supplied on the SIZE card. Those values have nothing to do with the actual corrections for absorption as applied to the data: they just report the EXPECTED range.Some correction packages (e.g. SADABS) will provide only one 'relative-correction-factor'. In such cases, Tmax should be given as  Tmax-expected and Tmin = relative-correction-factor * Tmax.

PLAT242 ：Type_2 Test for unusually low U(eq) as compared with bonded neighbors 。
The U(eq) value of an atom 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.

PLAT242 ：Type_2 Test for unusually low U(eq) as compared with bonded neighbors 。
The U(eq) value of an atom 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

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