Ring Finder

This modifier for OVITO finds closed rings formed by bonds, counts them, and visualizes them as polygonal facets. It only identifies rings whose sizes fall within a specified range, defined by minimum and maximum numbers of bonds.

Description

The modifier outputs the following things:

• Global attributes:
  • RingCount: The total number of rings found.
  • N-RingCount: Number of N-sized rings, where N is a number ranging from min_size to max_size.
• Data tables:
  • Ring size histogram: Histogram of the ring sizes (absolute bin counts).
  • N-ring list: List of the particle indices making up the individual N-sized rings, where N is a number ranging from min_size to max_size.
• Surface mesh (optional):
  • A visualization of the rings as polygonal facets. Each facet has a Ring Size property that indicates the size of the ring it represents. Using the color mapping feature of the surface mesh visual element, the facets can be colored according to their size.

Parameters

GUI name	Python name	Description	Default Value
Minimum ring size	min_size	Minimum size of the rings identified by the modifier.	3
Maximum ring size	max_size	Maximum size of the rings identified by the modifier.	9
Create polygons	create_mesh	Output a polygon facet for each ring.	True
Triangulate facets	triangulate_facets	Triangulate facets using an improved algorithm. Slower than the standard algorithm, but can provide better results for non-convex rings (see below).	False
Surface mesh vis	mesh_vis	Visual element controlling the appearance of the ring facets.

Example

With the standard triangulation algorithm, non-convex rings can produce artifacts:

The improved triangulation algorithm can handle non-convex rings better, but is slower:

Installation

This modifier is included in the OVITO Extension Directory and can be installed via the OVITO Pro GUI.

Alternatively, you can install the modifier from the command line using the ovitos command line tool that comes with OVITO Pro:

ovitos -m pip install --user git+https://github.com/ovito-org/RingFinder.git

The --user option is recommended and installs the package in the user's site directory.

If you are using a standalone Python interpreter or a Conda environment:

pip install git+https://github.com/ovito-org/RingFinder.git

Contact

Daniel Utt ([email protected])