Simplify Molecular Modeling with Backbone Attributes in SAMSON

Molecular modelers often face the mammoth task of sifting through complex molecular structures to find specific atom groups or perform focused simulations. SAMSON’s Node Specification Language (NSL) offers an elegant solution: backbone attributes. These attributes allow precise identification and manipulation of molecular backbones within large models, streamlining the workflow.

What Are Backbone Attributes?

Backbone attributes are a specialized attribute space in SAMSON’s NSL, associated with the backbone space (short name: s). They enable fine-grained querying and manipulation of backbone nodes in your molecular system.

For instance, you can use these attributes to filter nodes based on their visibility, material properties, or the number of specific atoms they contain (like carbons or hydrogens). Such precision helps in focusing on relevant parts of your model and improving efficiency in tasks like editing, visualizing, or exporting subsets.

Explore the Key Attributes

Here’s a breakdown of some useful attributes and how they can assist molecular modelers:

  • name (n): Identify backbone nodes by their names. For example, bb.n "L*" searches for nodes starting with “L”.
  • hasMaterial (hm): Check if a backbone node is associated with material. Use bb.hm for nodes with material and not bb.hm to exclude them.
  • numberOfAtoms (nat): Quickly filter nodes by the number of atoms they contain, e.g., bb.nat < 1000.
  • numberOfCarbons (nC), numberOfHydrogens (nH), and more: Target nodes based on the number of specific atom types, for instance, bb.nC 10:20 to find nodes with 10 to 20 carbon atoms.
  • visible (v): Manage and query visibility of nodes in your model with simple expressions like bb.v or not bb.v.

Work Smart with Expressions

The real power of backbone attributes lies in their ability to form expressions for customizable queries. For instance:

  • Find all visible backbone nodes with material: bb.v and bb.hm
  • Exclude backbone nodes with more than 20 carbons: not (bb.nC > 20)
  • Select nitrogen-rich backbones with a partial charge range: bb.nN > 5 and bb.pc 1.5:3.0

These examples demonstrate how NSL can significantly reduce the manual effort in molecular modeling by automating data filtering and focusing workflows on specific backbone regions.

Documentation is Key

To fully grasp the range of possibilities offered by SAMSON’s backbone attributes, it’s best to explore the detailed documentation page. Whether you’re a seasoned modeler or just starting, investing time in understanding these attributes will pay dividends by simplifying your projects.

SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.

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