CheckCIF-PLAT300-310
PLAT300 Type_4 Test for Fixed Partial Occupancy
This site is expected to be fully occupied but has been constrained (e.g. with a SHELXL FVAR variable) or fixed at a value less than 1.0. Please check for incomplete (substitutional) disorder handling.
(http://journals.iucr.org/services/cif/checking/PLAT300.html)
警告原因：某个原子的占有率被限定成了固定值。
解决策略：原子占有率最好按自由变量精修，除非有合理的解释(如在对称元素上或者已通过TG等试验确定)。
PLAT301 Type_3 Test for main residue(s) disorder %
Atom sites that are not fully occupied are counted. A large fraction of disordered atoms may be both a signal for serious structure analysis problems or less reliable/interesting results.
(http://journals.iucr.org/services/cif/checking/PLAT301.html)
警告原因：分子主体存在无序。
解决策略：无需解决，无序处理有合理解释即可。
PLAT302 Type_4 Test for (anion/solvent) disorder %
Atom sites that are not fully occupied are counted.
(http://journals.iucr.org/services/cif/checking/PLAT302.html)
警告原因：游离离子或者溶剂存在无序。
解决策略：无需解决，无序处理有合理解释即可。
PLAT303 Type_2 Test for more than 1 connection to Hydrogen Atoms
Hydrogen atoms are generally connected to only one other atom. A hydrogen atom between two oxygen atoms is a special case. Investigate whether this hydrogen atom is better described with a disorder model with two partially occupied sites. A difference map might show a double-well density.
(http://journals.iucr.org/services/cif/checking/PLAT303.html)
例：PLAT303_ALERT_2_B Full Occupancy H-Atom H8A with # Connections 3.00
解决策略：H8A重新加氢。H8A是否位于对称位置？请仔细考察其存在情况，在某一位置的任何原子的总占有率不能超过1。
PLAT304 Type_4 Test for non-integer number of atoms in residue
A non-integer number of atoms has been found in a residue.
某残基中发现了非整数个原子。
(http://journals.iucr.org/services/cif/checking/PLAT304.html)
警告原因：结构中某个(或某些)原子个数为非整数。
解决策略：检查是否占有率定错，改正即可。否则需要给出合理解释。
PLAT305 Type_2 Test for isolated Hydrogen Atoms
This test reports on hydrogen atoms that are not on bonding distance to any atom. This ALERT may indicate that the hydrogen atom refined to a non-bonding position or needs a symmetry operation to bring it to bonding distance. It also may indicate a problem with incompatible population parameters (e.g. C - H with population 0.8 and 0.9 respectively).
此检查报告结构中存在不处于与任何原子键合距离内的氢原子。此警告可能表明氢原子精修至一个非键合位置，或需要对称操作才能使其到达键合距离。它也可能表示存在不兼容的总体参数问题(例如C-H键长总体分别为0.8和0.9)。
(http://journals.iucr.org/services/cif/checking/PLAT305.html)
警告原因：结构中存在孤立氢原子。
解决策略：检查是否某原子上的氢原子由于不稳定而散架，删除该孤立氢原子后对有问题的原子重新加氢。
PLAT306 Type_2 Test for isolated Oxygen Atoms
This test reports on oxygen atoms that are not within bonding distance to any other atom in the structure. A common reason may be that no hydrogen atoms are given for a water molecule. Attempts should be made to locate those hydrogen atoms from a difference map.
(http://journals.iucr.org/services/cif/checking/PLAT306.html)
警告原因：存在游离的氧原子。
解决策略：一般都是游离的水分子，将水上加氢即可，如无法找到氢键受体需给出合理解释。
PLAT307 Type_2 Test for isolated Metal Atoms
This test reports on metal atoms that are not bonded or at coordination distance of other atoms. Isolated ions are very unusual (or non-existent ?)
(http://journals.iucr.org/services/cif/checking/PLAT307.html)
警告原因：存在游离的金属原子。
解决策略：检查原子类型是否定错。
PLAT308 Type_2 Test for single bonded Metal Atoms
This test reports on single bonded (coordinated) metal atoms/ions. This represents a very unusual situation. There are literature examples where such a 'single bonded metal' was shown to be a halogen.
此检查报告单键(配位的)金属原子/离子。这是一个极不寻常的情况。有一个例子是某文献报道的这种“单键金属”后被证明其实是卤素。
(http://journals.iucr.org/services/cif/checking/PLAT308.html)
警告原因：存在单配位的金属原子。
解决策略：检查原子类型是否定错。
PLAT309 Type_2 Test for single bonded Oxygen Atoms
Single bonded Oxygen with C-O > 1.3 Angstrom. Missing H-Atom ? Check
(http://journals.iucr.org/services/cif/checking/PLAT309.html)
警告原因：C-O键键长过长，应为单键。
解决策略：若确定为单键，则给氧上加氢。若确定为双键，则限制其键长落在碳氧双键键长范围内。否则需给出合理解释。
PLAT310 Type_2 Test for 'too close' (symmetry related) full weight atoms
This test identifies (very) short contacts between atoms that only becomes apparent after the application of symmetry on the primary coordinate set.
此检查识别原子之间(非常)短的接触，这种接触只有在主体坐标系上应用对称性之后才变得明显。
(http://journals.iucr.org/services/cif/checking/PLAT310.html)
警告原因：结构中存在距离过近的原子(通常需要进行对称操作才能发现)。
解决策略：通过限制其距离进行解决。若不能解决，给出合理解释即可。
