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Non-Hermitian Hamiltonian Approach for Two-Dimensional Coherent Spectra of Driven Systems
Hao-Yue Zhang1,2, Yi-Xuan Yao1,2, Bin-Yao Huang1,2,3
1School of Physics and Astronomy, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
Journal of Chemical Theory and Computation
|April 9, 2025
Summary
The non-Hermitian Hamiltonian (NHH) method offers a more suitable approach than the response-function (RF) formalism for analyzing systems using two-dimensional coherent spectroscopy (2DCS), especially when including relaxation and control fields.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Theoretical Chemistry
Background:
- Two-dimensional coherent spectroscopy (2DCS) is a powerful technique for high-resolution analysis.
- The response-function (RF) formalism has been the standard theoretical framework for 2DCS.
- Limitations exist in the RF formalism for complex systems.
Purpose of the Study:
- To compare the non-Hermitian Hamiltonian (NHH) method with the RF formalism for 2DCS analysis.
- To evaluate the suitability of the NHH method for systems with relaxation and control fields.
- To introduce quasi-Green functions for enhanced analysis within the NHH method.
Main Methods:
- Comparison of NHH and RF formalisms in a three-level system.
- Simulation of 2DCS signals and population dynamics.
- Application of the NHH method to a Rh(CO)2C5H7O2 (RDC) system in hexane.
Main Results:
- The NHH method provides analytical solutions for dominant Liouville paths via quasi-Green functions.
- NHH simulations for RDC in hexane show good agreement with experimental data.
- NHH method, despite overestimating relaxation, reveals distinct pathways compared to RF formalism.
Conclusions:
- The NHH method is more appropriate than the RF formalism for investigating systems with relaxation and control fields using 2DCS.
- The NHH method offers a more comprehensive understanding of dynamic processes in spectroscopic analysis.
- Quasi-Green functions enhance the analytical capabilities of the NHH method for complex systems.
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