THE THRESHOLD PHOTOELECTRON SPECTRUM OF SiH₂ AS MODELED WITH MCTDH

Coudert, L. H.

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https://hdl.handle.net/2142/122376 Copy

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Title

THE THRESHOLD PHOTOELECTRON SPECTRUM OF SiH₂ AS MODELED WITH MCTDH

Author(s)

Coudert, L. H.

Contributor(s)

• Hartweg, Sebastian
• Garcia, G. A.
• Loison, J.-C.
• Boyé-Peronne, Séverine
• Gans, Bérenger
• Chen, N.

Issue Date

2023-06-19

Keyword(s)

Comparing theory and experiment

Abstract

Although the ground X̃¹A₁ electronic state of silylene SiH₂ is fairly well characterized, fewer results are available about its first excited triplet a˜³B₁ electronic state and about its cationic species SiH−2⁺. The ground electronic state of the latter is split into bent X̃+²A₁ and linear Ã⁺²B₁ doublet electronic states by the Renner-Teller coupling. Threshold photoelectron (TPE) spectroscopy has been used to obtain spectroscopic information about the cationic species SiH⁺ of silylene and about the first excited triplet electronic state of neutral SiH₂. The TPE spectrum, recorded at Synchrotron SOLEIL from 7.5 to 11.5 eV using VUV synchrotron radiation, displays several sharp features and was modeled using wavepacket propagation. ωB97XD ab initio calculations were carried out using cc-PVTZ correlation-consistent basis set functions to retrieve 3-D potential energy surfaces for the four electronic states involved in the TPE spectrum. The MCTDH method was first used to obtain the 3-D vibrational wavefunctions of the neutral species X̃¹A₁ and a˜³B₁ electronic states using propagation in negative imaginary time. The wavefunctions thus obtained were then time- propagated in the potential energy surfaces of the coupled electronic states of the cationic species using also MCTDH. The photoionisation cross-section was at last computed as the Fourier transform of the auto-correlation function. In the talk, the results of the rovibronic energies calculation will be reported and the experimental TPE spectrum will be compared to the theoretical one. The importance of the Renner-Teller coupling will be assessed and the vibrational reproduces the experimental spectrum will be evaluated.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122376

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