Operator Formulation of Feynman Path Centroid Dynamics for Rotations.

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Molecular Dynamics

Background:

• Centroid Molecular Dynamics (CMD) is a powerful technique for simulating molecular systems.
• Simulating rotational degrees of freedom in quantum systems presents significant challenges.
• Existing methods often rely on discretized path integrals, which can be computationally intensive.

Purpose of the Study:

• To develop an operator formulation of centroid molecular dynamics (CMD) for rotational degrees of freedom.
• To enable phase-space mapping without discretized path integrals.
• To calculate approximate Kubo-transformed time correlation functions for rotational motion.

Main Methods:

• An operator formulation of CMD is presented.
• The quasi-density operator concept is utilized for phase-space mapping.
• The particle on a ring serves as an illustrative example for numerical validation.

Main Results:

• The proposed approach provides accurate results for linear operators compared to exact diagonalization.
• Rotational CMD demonstrates excellent agreement with quantum dynamics of spin-1 systems at low temperatures.
• The method avoids the need for discretized path integrals.

Conclusions:

• The operator formulation of CMD is a viable and accurate method for simulating rotational quantum dynamics.
• This approach offers a computationally efficient alternative to traditional path integral methods.
• The findings have implications for understanding molecular behavior at low temperatures.