研究目的
To compute and compare the total photoionization cross sections of valence excited states of helium, water, sulfur dioxide, molecular nitrogen, and carbon monoxide using an asymmetric-Lanczos-based formulation of the equation-of-motion coupled cluster singles and doubles approach, and to validate these results against theoretical and experimental data.
研究成果
The asymmetric-Lanczos-based EOM-CCSD approach provides accurate photoionization cross sections for valence excited states, showing good agreement with theoretical and experimental data. The methodology is validated for helium, water, sulfur dioxide, molecular nitrogen, and carbon monoxide, demonstrating its potential for guiding experimentalists in studying transient states of molecules.
研究不足
The study relies on computational methods that may have inherent approximations, such as the use of L2 basis sets which lack continuum asymptotic information. The comparison with experimental data is limited by the availability of such data for the studied systems.
1：Experimental Design and Method Selection:
The study employs an asymmetric-Lanczos-based formulation of the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) approach to compute excitation energies and oscillator strengths. The photoionization cross sections are generated using analytic continuation based on Padé approximants and the Stieltjes imaging technique.
2：Sample Selection and Data Sources:
The study focuses on the first two electronically excited states of helium, water, sulfur dioxide, molecular nitrogen, and carbon monoxide. Theoretical results are compared with algebraic diagrammatic construction [ADC(2)] and ADC(2)-x calculations and available experimental data.
3：List of Experimental Equipment and Materials:
Computational methods are implemented in a development version of the Dalton program package. Dunning’s correlation consistent basis set aug-cc-pVTZ is used, enriched with continuum-like basis functions.
4：Experimental Procedures and Operational Workflow:
The methodology involves calculating excitation energies and oscillator strengths, generating pseudospectra, and applying Padé approximants and Stieltjes imaging to reconstruct photoionization cross sections.
5：Data Analysis Methods:
The results are analyzed by comparing computed photoionization cross sections with theoretical and experimental data, assessing the agreement and discrepancies.
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