Selecting the wrong atoms can quietly derail a molecular modeling task. You may intend to inspect one residue, move a ligand, or apply a visual model to a protein—but a broad viewport selection can include more than you meant to change. A dependable approach is to treat selection as a small workflow: choose what can be selected, make the selection, verify it, and only then act.
1. Decide what the viewport is allowed to select
In the viewport, use a selection editor to pick nodes with the mouse. Before selecting, check the selection filter in the top-right corner. It controls which node types can be highlighted and selected. This matters when a structure contains several kinds of nodes: filtering helps narrow the selection to the type you want to work with.
With the Rectangle selection editor, click nodes to select them. To select a region, drag outside selected nodes to create a rectangle. Hold Ctrl on Windows/Linux or Cmd on macOS to add nodes to the current selection; hold Alt to remove nodes. Use the right mouse button to open the context menu. The editor shortcut is R.
2. Use the Document view when hierarchy is clearer than geometry
It can be difficult to click a particular structural component in a crowded 3D view. The Document view offers another route: click nodes in the hierarchy to select them and highlight them in the viewport. Use Shift and Ctrl or Cmd for multi-selection.
You can also filter the Document view by entering text or a Node Specification Language (NSL) expression, then pressing Enter to select matching nodes. This is useful when you know what you are looking for by name or by a selection criterion, rather than by its screen position. The selection filter shown in the Document view helps you narrow the nodes displayed there.
3. Verify the selection before changing anything
Selection is not just a preliminary step: it determines what many subsequent actions apply to. Before moving nodes, editing properties, or adding a visual model, pause to check what is selected. The bottom of the Document view displays a selection summary. Click it to open contextual actions for the current selection.
If the selection is not what you expected, adjust it before proceeding. In the viewport, add or remove nodes with the modifier keys, or use the Document view to select the intended hierarchy. This quick check is especially helpful before applying changes to a large or complex structure.
4. Use Find when a precise query is easier than clicking
For selections described by criteria, use Select > Find. The shortcut is Ctrl+F on Windows/Linux or Cmd+F on macOS. Find uses the Node Specification Language to select nodes that match an expression. It can be a more direct option than searching through a long hierarchy or trying to target small objects in the viewport.
A simple habit that prevents mistakes
For routine work, follow this sequence: set the selection filter, select through the viewport or Document view, inspect the selection summary, and then run the intended command. Use Find when your selection is better expressed as a query. These options complement one another: the viewport is spatial, the Document view exposes hierarchy, and Find lets you specify matching nodes.
For more selection techniques, see Selecting and Selecting using Editors. The Node Specification Language guide explains query-based selection. For the broader interface workflow, continue with the SAMSON Quick Start Guide.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.