Molecular modelers often grapple with challenges in atomic structure manipulation at nanoscale resolution. Whether it’s selecting specific atoms for custom modifications or isolating structures within a defined geometric space, achieving precision can be daunting without the right tools. The Simple Script Extension in SAMSON simplifies this by enabling users to perform advanced atom selection with a scripting language based on mathematical expressions. This blog post provides an approachable introduction to this powerful tool and explores how to enhance your modeling workflows.
Why Simple Script?
The Simple Script Extension allows you to precisely select and manipulate atoms based on their properties, such as position, visibility, or even chemical attributes like element type. By employing mathematical expressions and logical operators in a scripting interface, this extension empowers users to go beyond manual selection and fine-tune their atom selections for various tasks. Whether you need to isolate a set of atoms for visualization or define a region to apply modifications, Simple Script has you covered.
How It Works
The script utilizes predefined variables corresponding to atomic properties. For instance:
a.x,a.y,a.z: 3D coordinates of an atoma.elementanda.symbol: Element name or symbola.visibilityFlag(ora.vf): Visibility statusa.chainID: Chain index to which an atom belongs
This flexibility makes it easy to frame customized scripts for atom selection. For example, to select all Carbon and Hydrogen atoms, you can write:
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if (a.element == 'Carbon' or a.symbol == 'H') n.selectionFlag := 1; else n.selectionFlag := 0; |
The above code ensures that only Carbon and Hydrogen atoms are selected, which can then be isolated or modified further.
Geometric Selections
What if you need to select atoms within a specific geometric shape, such as inside a sphere or cylinder? With Simple Script, that’s straightforward. Here’s an example to show atoms inside a sphere of radius 10 units centered at (0,0,2):
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if ((a.x^2 + a.y^2 + (a.z - 2)^2) < 100) a.visibilityFlag := 1; else a.visibilityFlag := 0; |
This script hides all atoms outside the specified sphere, simplifying visualization and potential data manipulations for the selected group.
A Visual Example
Observe the power of structured scripting in action:
Using a variation of the above approach, a cylinder of atoms is cut from a quartz crystal based on their exact positions, creating a pure, defined structure for further study.
Ready to Try?
Dive into the Simple Script Extension and let it transform how you manipulate and analyze atomic-scale data. Additionally, if you’re looking for even simpler choices, SAMSON’s Atoms Selector Extension minimizes scripting even further, allowing you to directly input mathematical expressions for atom selection without writing full scripts.
For a detailed guide and more examples, visit the official documentation.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at SAMSON Connect.