Atomic momentum distributions in polyatomic molecules in rotational-vibrational eigenstates

Area of Science:

• Quantum mechanics
• Molecular physics
• Computational chemistry

Background:

• Understanding molecular behavior requires analyzing atomic motion.
• Rovibrational states influence molecular structure and dynamics.
• Atomic momentum distributions offer insights into molecular bonding and vibrations.

Purpose of the Study:

• To develop a quantum mechanical method for calculating atomic momentum distributions in polyatomic molecules.
• To investigate the presence or absence of oscillations in atomic momentum distributions for specific triatomic molecules.
• To elucidate the origin of observed oscillations in atomic momentum distributions.

Main Methods:

• A novel quantum mechanical method was formulated.
• The theory was applied to triatomic molecules (H2O and CO2) in their rovibrational ground states.
• Rigid rotor models were used to analyze atomic momentum distributions.

Main Results:

• The quantum method successfully calculated atomic momentum distributions for H2O and CO2.
• Oscillatory changes were detected in the proton momentum distribution of nonlinear H2O.
• No such oscillations were found in the oxygen atom's momentum distribution for linear CO2.
• The oscillations were attributed to the quantum-mechanical delocalization of atoms.

Conclusions:

• The developed quantum method provides a new tool for molecular analysis.
• Quantum delocalization of atoms is responsible for oscillations in momentum distributions.
• The findings highlight differences in atomic behavior between nonlinear and linear triatomic molecules.