Electronic coarse-graining

The goal of electronic coarse-graining of a semiconductor is to construct a minimal local basis providing an accurate description of the frontier orbitals and near-gap excitations under small atomic displacements. It serves as a basis for first-principles electron-phonon models. In particular, it gives electronic intermolecular couplings, which themselves provide electronic connectivity map of the semiconductor.

Requirements:

1. Stability/robustness of the coarse-grained basis wrt molecular fluctuations at ambient conditions
2. Robustness and scalability of the coarse-graining algorithm
3. Quality control of the coarse-grained basis and matrix elements
4. Accurate extrapolation to infinite system (if needed)

Applications

• Determination of the electronic structure of an infinite system from calculations of its fragments (if conventional methods are unsuitable) [2D pnictogens, polymers]
• Basis optimization and calculation of matrix elements of electron-phonon Hamiltonian [charge transport in molecular solids, review on modeling]
• Basis optimization for non-adiabatic molecular dynamics
• In-depth analysis of electronic structure including a map of electronic connectivity [polymers]
• Generation of high-level descriptors for machine learning
• Hybrid approaches like QM/TB

References

• Fragmentation methods
• Localized molecular orbitals
• Wannier functions
• Tight-binding methods
• Tight-binding approaches in Conjugated polymers
• Multiscale modeling
• Multiscale approaches in Classical molecular dynamics

Presentations

• Slides from TUM seminar 2024
• Additional slides introducing organic semiconductors

Publications

• Electronic coarse-graining of long conjugated molecules: Case study of non-fullerene acceptors, JCP 159, 024107 (2023) [pdf, slides]