Computational Insights into the Vibrational States of Methanol

Recent research has focused on the vibrational states of methanol (CH₃OH), utilizing a full-dimensional (12D) computational approach. The study, conducted by Ayaki Sunaga, Gustavo Avila, and Edit Matyus, employed the GENIUSH-Smolyak method alongside a potential energy surface developed by Qu and Bowman in 2013. The researchers reported that all vibrational energies achieved convergence better than 0.5 cm⁻¹, extending up to the first overtone of the CO stretch, approximately 2000 cm⁻¹ beyond the zero-point vibrational energy.

The findings include the assignment of about seventy torsion-vibration states, with computed vibrational energies aligning closely with existing experimental data, generally within a few cm⁻¹. This accuracy supports the reliability of the potential energy surface used in the calculations.

The methodology involved curvilinear normal coordinates and path-following coefficients, which helped minimize the coupling between small- and large-amplitude motions. The researchers emphasized the importance of maintaining the molecular symmetry of C₃v(M) across various geometries to accurately describe the degeneracy in this flexible molecular system.

These results may serve as a computational reference for various fields, including fundamental spectroscopy and astrochemistry, and could assist in investigations into variations in the proton-to-electron mass ratio using methanol as a model molecule. The implications of this research extend to enhancing our understanding of molecular dynamics and interactions in complex chemical systems.