原文如下：
Get esd's on geometric measurements
Olex2 can calculate esd's on a variety of geometric measurements, also if a CIF is loaded into Olex2 then esd's available in the CIF (bond lengths and the angles) will be displayed in the tooltip when hovering over the bonds or selection of the bonds; use the 'sel' command to print the values in the console.
To calculate the esd's Olex2 need the variance-covariance matrix. This can be readily produced by shelxl when refining with a negative MORE instruction (like MORE -1). It also will be soon available from the smtbx refinement. Once the matrix file is available, the geometric parameters can be easily calculated by selecting:
a bond or two atoms – length two bonds or three atoms – angle four atoms - torsion angle and the tetrahedron volume a plane - RMSD and the centroid coordinates in fractional and Cartesian coordinates a plane and an atom - atom to plane and atom to plane centroid distances a plane and a bond - angle between the plane normal and the bond two planes - angle between the plane normals, plane centroid to plane centroid, plane to centroid and the shift between the plane centroids distances three planes - the angle between the plane centroids
Then type:
>>esd
to get the measurements with esd's.
Note that the current implementation of the esd calculation procedure does not consider symmetry constraints and gives esd's even for the symmetry related parameters.
譯文如下：
3.9. 獲取幾何測量的估計標準偏差(esd)Olex2可以計算各種幾何測量的估計標準偏差(esd, Estimated Standard Deviation)，若將CIF加載到Olex2中，當滑鼠懸停在鍵或選定鍵上時，工具提示中將顯示CIF中可用的esd(鍵長和角度)；使用'sel'指令在控制臺中列印這些數值。
為計算esd，Olex2需要方差-協方差矩陣。當使用負的MORE指令(如MORE -1)進行精修時，shelxl可很容易地獲得所需方差-協方差矩陣。它也很快將從smtbx精修中提供。一旦矩陣文件可用，幾何參數可以很容易地通過以下選擇進行計算：
一根鍵或兩個原子——鍵長(距離)
兩根鍵或三個原子——鍵角
四個原子——扭轉角和四面體體積
一個平面——RMSD和質心的分數坐標和笛卡爾坐標
一個平面和一個原子——原子到平面距離和原子到平面質心距離
一個平面和一根鍵——平面法線與該鍵夾角
兩個平面——兩個平面法線夾角、兩個平面質心間距、平面到質心間距以及兩個平面質心滑移間距
三個平面——三個平面質心形成的夾角
然後鍵入
>>esd
以獲取上述測量的esd。
請注意，esd計算程序的當前執行程序沒有考慮對稱性，甚至對對稱性相關參數也給出了esd。
本文輔助視頻如下：
https://www.bilibili.com/video/BV1ib411u7r2
Olex2視頻教程——指令mpln的使用https://www.bilibili.com/video/BV1ob411W79i
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