研究目的
Investigating efficient methods for calculating (resonance) Raman spectra using real-time time-dependent density functional theory (RT-TDDFT) and comparing these methods with traditional perturbation theory approaches.
研究成果
The study demonstrates that RT-TDDFT is a promising approach for efficiently calculating Raman spectra, including resonance Raman spectra and excitation profiles. The use of Pad′e approximants enables the excited state gradient method within an RT-TDDFT framework, showing good agreement with traditional perturbation theory methods.
研究不足
The study is limited by the adiabatic approximation in TDDFT, potential errors from numerical propagators, and the need for high computational resources for achieving sufficient resolution in frequency domain.
1：Experimental Design and Method Selection:
The study employs RT-TDDFT for calculating Raman spectra, comparing it with perturbation theory approaches. It focuses on short time approximations to the Kramers, Heisenberg, and Dirac polarizability tensor.
2：Sample Selection and Data Sources:
The study uses uracil and R-methyloxirane as model systems to validate the approaches.
3：List of Experimental Equipment and Materials:
Computational methods and software packages (CP2K, Turbomole) are used for simulations. Basis sets and functionals (PBE, PBE0, BP86) are specified.
4：Experimental Procedures and Operational Workflow:
Geometry optimizations, normal mode analyses, and real-time propagation runs are performed. Pad′e approximants are used for Fourier transforms to achieve high frequency resolution.
5：Data Analysis Methods:
The study compares absorption and Raman spectra obtained from RT-TDDFT and PT-TDDFT, evaluating the performance of Pad′e approximants and the excited state gradient method.
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