A Topology-Based Toolkit for Generalized Carbon Nanobelts

beltopkit is a specialized MATLAB package of source codes designed for the topological analysis and structural construction of generalized Carbon Nanobelts (CNBs). The toolkit supports a wide variety of molecular architectures, including untwisted, singly, and multiply twisted structures with both Hückel and Möbius topologies.

Author: Yang Wang Institution: Yangzhou University Email: yangwang@yzu.edu.cn ORCID: 0000-0003-2540-2199

If you utilize beltopkit in your research, please cite the associated preprint/publication:

• Y. Wang. A Unified Topological Framework for Representation and Construction of Generalized Carbon Nanobelts. ChemRxiv 2026, preprint: DOI:10.26434/chemrxiv.15001591/v1

1. Clone or download this repository to your local machine.

2. Launch MATLAB.

3. Add the beltopkit directory and its subfolders to your MATLAB path:

% Run this in the MATLAB Command Window
addpath(genpath('/path/to/beltopkit'))
savepath

To analyze the topological characteristics (path codes, RDS, Hückel/Möbius status, etc.) of representative generalized CNBs:

• Navigate to the demo/nomenclature/ directory within MATLAB.

• Run the following script:

demo_path_codes

• Detailed topological data and symmetry information will be printed directly to the Command Window.

To explore the configurational space and generate 3D coordinates:

• Navigate to the demo/construction/ directory.

• Möbius Topoisomer Enumeration: Run these scripts to generate nonequivalent Möbius CNBs from various parent molecules:

demo_MCNBs_CNB_12_12_12235   % From parent CNB (12,12)-12235
demo_MCNBs_octulene          % From Octulene
demo_MCNBs_expKek45          % From expanded [4,5]kekulene

• Interactive 3D Geometry Generation: To generate .xyz coordinates from specific topological path codes:

demo_gen_geom3d_from_pathcode

This script covers untwisted, singly, doubly, and triply twisted belts.

beltopkit outputs the topological characteristics of a given generalized CNB from its 3D atomic coordinates in an input xyz file or Gaussian output file.

• Path Code
• Path String
• Ring Directional Sequence (RDS)
• **Rings with the corresponding Indices of Atoms

The toolkit is validated against a wide range of theoretically significant and experimentally synthesized generalized CNBs, including untwisted, singly, and multiply twisted structures with both Hückel and Möbius topologies.

To perform batch demo on existing .xyz geometries and extract their topological parameters:

% Executes the automated nomenclature and topology analysis demo
demo_path_codes()

For individual file analysis:

[pathcode, pathstring, rds, ringcell] = belt_code('molecule.xyz');

beltopkit provides tools to explore the configurational space of nanobelts and generate initial 3D molecular geometries for quantum chemical calculations.

Automatically generate all nonequivalent Möbius topoisomers from a base CNB topology (e.g., [12,12] CNB or Octulene):

demo_MCNBs_CNB_12_12_12235()
demo_MCNBs_octulene()

Transform topological path codes into 3D molecular coordinates (.xyz format) via an interactive menu:

% Launches the interactive construction menu
demo_gen_geom3d_from_pathcode()

The toolkit includes a "round-trip" verification protocol that re-calculates path codes from generated geometries to ensure absolute structural integrity.

• beltopkit/: Root directory of beltopkit, containing all functioning codes

• beltopkit/demo/nomenclature/: Demostration scripts for nomenclature & topology analysis

• beltopkit/demo/construction/: Demostration scripts for 3D structural generation and topoisomer enumeration.

• belt_code.m: Core engine for topology analysis and nomenclature.

• gen_belt_from_pathcode.m: Core engine for 3D coordinate generation.

• genMCNBs_from_CNB_topo.m: For Möbius topoisomer enumeration.

• decode_belt_code.m: Parser for topological string descriptors.

• write_xyz.m: Utility to export molecular data to standard .xyz format.

Copyright (c) 2026 Yang Wang. All rights reserved.

This software is provided for academic and non-commercial use only. For commercial inquiries or licensing, please contact the author directly.