Saved in:
| Main Authors: | , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.21279 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866915515796029440 |
|---|---|
| author | Marek, Štěpán Wilhelm, Jan |
| author_facet | Marek, Štěpán Wilhelm, Jan |
| contents | We present a real-time propagation method for computing linear and nonlinear optical properties of molecules based on the Bethe-Salpeter equation. The method follows the time evolution of the one-particle density matrix under an external electric field. We include electron-electron interaction effects through a self-energy based on the screened exchange approximation. Quasiparticle energies are taken from a prior $GW$ calculation to construct the effective single-particle Hamiltonian and we represent all operators and wavefunctions in an atom-centered Gaussian basis. We benchmark the accuracy of the real-time propagation against the standard linear-response Bethe-Salpeter equation using a set of organic molecules. We find very good agreement when computing linear-response isotropic polarizability spectra from both approaches, with a mean absolute deviation of 30~meV in peak positions. Beyond linear response, we simulate second harmonic generation and optical rectification in a non-centrosymmetric molecule. These phenomena are not captured by the commonly used linear-response Bethe-Salpeter equation. We foresee broad applicability of real-time propagation based on the Bethe-Salpeter equation for the study of linear and nonlinear optical properties of molecules as the method has a similar computational cost as time-dependent density functional theory with hybrid functionals. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_21279 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Linear and Nonlinear Optical Properties of Molecules from Real-Time Propagation Based on the Bethe-Salpeter Equation Marek, Štěpán Wilhelm, Jan Computational Physics Chemical Physics We present a real-time propagation method for computing linear and nonlinear optical properties of molecules based on the Bethe-Salpeter equation. The method follows the time evolution of the one-particle density matrix under an external electric field. We include electron-electron interaction effects through a self-energy based on the screened exchange approximation. Quasiparticle energies are taken from a prior $GW$ calculation to construct the effective single-particle Hamiltonian and we represent all operators and wavefunctions in an atom-centered Gaussian basis. We benchmark the accuracy of the real-time propagation against the standard linear-response Bethe-Salpeter equation using a set of organic molecules. We find very good agreement when computing linear-response isotropic polarizability spectra from both approaches, with a mean absolute deviation of 30~meV in peak positions. Beyond linear response, we simulate second harmonic generation and optical rectification in a non-centrosymmetric molecule. These phenomena are not captured by the commonly used linear-response Bethe-Salpeter equation. We foresee broad applicability of real-time propagation based on the Bethe-Salpeter equation for the study of linear and nonlinear optical properties of molecules as the method has a similar computational cost as time-dependent density functional theory with hybrid functionals. |
| title | Linear and Nonlinear Optical Properties of Molecules from Real-Time Propagation Based on the Bethe-Salpeter Equation |
| topic | Computational Physics Chemical Physics |
| url | https://arxiv.org/abs/2507.21279 |