Generalized approximation to the reaction path: the formic acid dimer case.

Area of Science:

• Chemical Physics
• Theoretical Chemistry
• Spectroscopy

Background:

• The formic acid dimer exhibits complex proton transfer dynamics.
• Understanding these dynamics is crucial for molecular reaction mechanisms.

Purpose of the Study:

• To develop and apply a novel set of mass-weighted internal coordinates for studying the double proton transfer reaction in the formic acid dimer.
• To analyze the impact of dimer dissociative motion on vibrational state dynamics.

Main Methods:

• Derivation of mass-weighted internal coordinates using an optimization procedure based on kinematic rotations.
• Application of these coordinates to model the double proton transfer in formic acid dimer.
• Analysis of vibrational states, including the symmetric OH-stretch region.

Main Results:

• Identified three significant internal coordinates that define the reaction space for proton transfer.
• Remaining vibrational modes were treated using a harmonic approximation.
• Observed four doublets in the symmetric OH-stretch vibration frequency region with specific splittings (2.76, 0.07, 0.60, 4.03 cm⁻¹).

Conclusions:

• The developed coordinate set effectively captures the essential dynamics of double proton transfer in formic acid dimer.
• The study provides insights into the interplay between dissociative motion and vibrational states.
• The identified spectral features offer a basis for experimental verification.