Anharmonic Vibrational Spectroscopy of Germanium-Containing Clusters, GeC_4- and GeSi_4- (x = 0-4), for Interstellar...

Area of Science:

• Astrochemistry
• Computational Chemistry
• Spectroscopy

Background:

• The interstellar medium (ISM) composition is increasingly detailed.
• Carbon and silicon are common in the ISM, but germanium molecules are rare.
• Germanium's role in the ISM is poorly understood.

Purpose of the Study:

• To theoretically study tetra-atomic germanium carbide/silicide clusters.
• To calculate vibrational and rotational spectroscopic properties.
• To aid in the potential identification of these molecules in the ISM.

Main Methods:

• High-level theoretical calculations using CCSD(T)-F12a(b)/cc-pVT(Q)Z-F12.
• Analysis of harmonic and anharmonic vibrational frequencies.
• Calculation of rotational constants for various molecular structures.

Main Results:

• Investigated rhomboidal, diamond, and trapezoidal GeCx and GeSix clusters (x=0-4).
• Identified r-Ge2C2 as a promising candidate for detection (ν4 mode at 802.7 cm⁻¹).
• Other potentially detectable molecules include r-Ge3C, r-GeSi3, d-GeC3, r-GeC3, and t-Ge2C2.

Conclusions:

• Theoretical spectroscopic data are crucial for ISM chemical composition studies.
• Germanium-containing molecules, particularly r-Ge2C2, may be detectable with instruments like JWST.
• This work provides a reference database for identifying new interstellar molecules.