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魏超金蟲 (正式寫手)
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有3個B錯誤,請大家?guī)兔鉀Q一下 已有1人參與
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Alert level B PLAT230_ALERT_2_B Hirshfeld Test Diff for O2 -- C1 .. 13.0 su PLAT417_ALERT_2_B Short Inter D-H..H-D H2A .. H7A .. 1.87 Ang. PLAT420_ALERT_2_B D-H Without Acceptor O7 - H8A ... ? -------------------------------------------------------------------------------- 分別為 PLAT230 Type_2 Hirshfeld Rigid-Bond Test (Acta Cryst (1976),A32,239-244 -------------------------------------------------------------------------------- The components of the anisotropic displacement parameters along chemical bonds are assumed to be equal in magnitude. Large differences might indicate contamination of these parameters with other (unresolved) effects such as (substitutional) disorder, model or data errors and/or over-refinement. Atomic 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. Note: The original 'Hirshfeld-test' was defined in absolute terms (see F.L.Hirshfeld, Acta Cryst. (1976). A32, 239-244). The current test is with reference to the associated standard uncertainty. PLAT417 Type_2 Test for short non-bonding inter D-H..H-D contacts -------------------------------------------------------------------------------- Short non-bonding inter D-H..H-D contacts may be related to disordered or misplaced H-atoms. Experience has shown that any intermolecular H...H separation of less than 1.8 Angstroms between unit-occupancy H atoms is a clear indicator that one or both of these H atoms may be wrongly placed. PLAT420 Type_2 Test for D-H without acceptor -------------------------------------------------------------------------------- Potential hydrogen bond donors are checked for the presence of suitable acceptors using commonly used (Jeffrey) H-bond criteria. As a general rule there should be an acceptor for each donor. Exceptions are very rare for O-H and more common for -NH and -NH2. A common error is an -OH on a calculated position pointing in the wrong direction. [ Last edited by 魏超 on 2013-2-24 at 10:01 ] |
金蟲 (正式寫手)
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木蟲 (正式寫手)
木蟲 (正式寫手)
銅蟲 (小有名氣)

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