Volume 2 Chapter 3 3D-Constrain Sub-menu CENTROID

Function

CENTROID is used to setup the centroid of a set of points.

A maximum of 10 points can be specified in setting up a centroid.

In a single search test there can be a maximum of 9 centroids.

Centroids are automatically named Xn with n=1 to 9.

Example

Select or type items for CENTROID. If necessary reselect CENTROID
to end input.
Select CANCEL to cancel command.

Select atoms 1,2,3,4,5,6 in turn.
As each atom is selected a red + appears at that atom in the fragment and the atom number appears in the dialogue area.
Select CENTROID
In the summary area we now have:
```
X1  1  2  3  4  5  6
```
This line is displayed in red to indicate that it is a SETUP command.
The red crosses at the selected atoms now vanish.
If INSTRUCTIONS is toggled 'ON' then in the fragment a red label X1 appears at the centroid position with red lines joining it to the selected atoms.
In the dialogue area we now have the "home" prompt:
```
Search for ALL crystal fragments
OVERLAP of crystal fragments permitted
Select a menu command or TO-BUILD to return to the BUILD menu.
```
The resultant command in the instruction document is:
```
SETUP  X1   1  2  3  4  5  6
```

Note: Dummy points can not be used in setting up a centroid.

If, for example, you select the dummy point D1 then reselecting CENTROID to end input gives:

Beep
*XVPCHK* Invalid item D1
Please press <RETURN> to continue.  Thank you.

Related Commands

SETUP DUMMY, SETUP PLANE, SETUP VECTOR