Communication: conical intersections between vibrationally adiabatic surfaces in methanol.

Area of Science:

• * Quantum Chemistry
• * Molecular Spectroscopy
• * Chemical Physics

Background:

• * Understanding molecular vibrations and energy transfer is crucial in chemical dynamics.
• * Conical intersections (CIs) are critical points in molecular potential energy surfaces where electronic states degenerate, facilitating non-adiabatic transitions.
• * Methanol's vibrational dynamics, particularly involving asymmetric CH stretches, present a complex system for theoretical study.

Purpose of the Study:

• * To report the identification and characterization of seven conical intersections (CIs) in methanol.
• * To investigate the role of geometric phase in the context of these CIs.
• * To explore the implications of CIs for energy transfer processes in methanol.

Main Methods:

• * Ab initio calculations were performed to determine the energies of adiabatic surfaces.
• * The study employed an extended Zwanziger and Grant (E⊗e) model to describe the ab initio data.
• * The identified CIs were analyzed in relation to the torsion and COH bend angles.

Main Results:

• * Seven conical intersections (CIs) were found between vibrationally adiabatic surfaces in methanol.
• * The ab initio data were accurately represented by an extended Zwanziger and Grant (E⊗e) model.
• * The CIs were found to be dependent on the torsion and COH bend angles of methanol.

Conclusions:

• * The identified CIs play a significant role in understanding the geometric phase in methanol.
• * Conical intersections are important sites for localized energy transfer processes.
• * The study provides insights into the complex vibrational dynamics and non-adiabatic effects in methanol.