Anharmonic rovibrational analysis for disilacyclopropenylidene (Si2CH2)

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• The electronic singlet potential energy surface of Si2CH2 is explored.
• A peculiar hydrogen-bridged (Si···H···Si) structure is identified as the global minimum.

Purpose of the Study:

• To accurately determine the quartic force field for Si2CH2.
• To predict vibration-rotation coupling constants, rotational constants, centrifugal distortion constants, and vibrational frequencies for six isotopologues.
• To investigate anharmonic corrections for vibrational motions.

Main Methods:

• Ab initio coupled-cluster theory with single and double excitations and perturbative treatment for triple excitations [CCSD(T)].
• Correlation consistent core-valence quadruple zeta (cc-pCVQZ) basis set.
• Vibrational second-order perturbation theory (VPT2).

Main Results:

• An accurate quartic force field for Si2CH2 was determined.
• Key molecular properties including rotational and vibrational frequencies were predicted for six isotopologues.
• Anharmonic corrections for H-bridged bonds were found to exceed 5% of harmonic frequencies.

Conclusions:

• The theoretical investigation provides a detailed characterization of the Si2CH2 molecule.
• Significant anharmonic effects highlight the need for accurate theoretical methods.
• Experimental detection and characterization of disilacyclopropenylidene (Si2CH2) are strongly encouraged.