Move a molecular group without losing its shape

When you need to reposition several atoms, the important question is not just where to move them—it is whether their positions relative to one another should stay the same. A small change in the Inspector’s Relative setting can mean the difference between moving a group as a unit and assigning every selected atom the same position.

This workflow is useful when adjusting a group of atoms while preserving its internal arrangement. It also helps prevent a common source of confusion: the Inspector displays the values of the last-selected node of a given type, but an attribute edit can affect every selected node of that type.

Move the selection while preserving its arrangement

First, select the atoms you want to move. Open the Inspector from Interface > Inspector, or use Ctrl+2 on Windows and Linux, or Cmd+2 on Mac. You can also open it from the selection’s context toolbar.

To find the position controls quickly, type position into the Inspector’s filter. With the Relative option on, changing the position moves the selected atoms while retaining their relative positions. In practical terms, the group changes location without turning its internal arrangement into a set of overlapping atoms.

Multiple atoms selected in the Inspector
Select the atoms you intend to move, then inspect their position controls.
Changing the positions of multiple selected atoms
With Relative enabled, the selected atoms move while keeping their relative positions.

Know what happens when Relative is off

If you turn Relative off, the selected atoms’ positions are changed to the same value. That is a different operation from moving the group as a whole, and it can substantially alter the arrangement you intended to preserve. If you are unsure which behavior you need, leave Relative on for a group move and check the result in the molecular view.

If an edit does not produce the expected result, SAMSON’s history mechanism lets you undo it. Undo is useful for testing the difference between the two settings, but checking the option before editing is the simplest way to avoid an unwanted change.

Read the Inspector carefully with multi-selection

The Inspector organizes attributes by node type and attribute group. When several atoms are selected, the value shown for an attribute reflects the last-selected atom—not an average or a summary of the whole selection. At the same time, if you modify an attribute, the change is applied to all selected nodes of that type.

That distinction matters whenever you inspect or edit a group. Treat the displayed value as a useful reference for one selected atom, rather than proof that every selected atom already has that value. For position edits, use the Relative setting to control how the selection responds.

A quick, cautious workflow

  1. Select the atoms you want to reposition.
  2. Open the Inspector and filter for position.
  3. Confirm that Relative is on if you want to preserve the group’s internal arrangement.
  4. Change the position and inspect the result.
  5. Undo through history if the result is not what you intended.

This approach makes a multi-atom edit easier to reason about: select deliberately, understand which nodes an edit affects, and verify the setting that determines whether the atoms move together or share one position.

For more details, see the SAMSON Inspector documentation.

Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.

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