Exciton Absorption

This repository provides a codebase for parsing Q-Chem output and constructing tight-binding Hamiltonians for excitonic systems to compute absorption spectra. The codebase is organized into two main stages and supports flexible system dimensionality (1D, 2D, 3D) for model building and comparison with experiment.

Dependencies

• Python ≥ 3.7
• NumPy
• JSON (Python standard library)

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Workflow

Stage 1: Extract Data from Q-Chem Output

Run extract.py to parse Q-Chem .out files and generate corresponding .json files.

Command Format

python3 extract.py H2OBPC PBE0

Stage 2: Generate Tight Binding Hamiltonian

Run tb_ham.py using the generated JSON to construct the model Hamiltonian. The script supports 1D, 2D, and 3D arrangements with customizable coupling schemes and spectral parameters.

Command Format

Examples for comparison with experimental data:

1D-AB model:

python3 tb_ham.py H2OBPC PBE0 "600,1,1" --zigzag "1" --coupling "J_coul" --rcut "26" --eshift 0.4 --gamma 0.45 --digitized ../systems/raw-sum-tabs.txt

2D model:

python3 tb_ham.py H2OBPC PBE0 "60,10,1" --coupling "J_coul" --rcut "17" --eshift 0.4 --gamma 0.45 --digitized ../systems/raw-sum-tabs.txt

3D model:

python3 tb_ham.py H2OBPC PBE0 "30,10,2" --coupling "J_coul" --rcut "10" --eshift 0.4 --gamma 0.45 --digitized ../systems/raw-sum-tabs.txt

Acknowledgments

This material is based on work supported by National Science Foundation under NSF OAC-2311442. YS and PH were supported by NSF grant OAC-2311442 for part of this study, specifically the code development for modeling exciton absorption spectra.

Contributing

• New features, bug fixes, documentation, tutorial examples, code testing is welcome in the developer community!

  • If you find any bugs please form a bug report/issue.
  • If you have a fix please consider adding a pull request