Simulations of rigid bodies in an angle-axis framework

Area of Science:

• Computational chemistry
• Molecular modeling

Background:

• Geometry optimization is crucial for analyzing molecular systems.
• Current methods for rigid body systems can be computationally intensive.
• Coarse-grained models simplify complex molecular systems.

Purpose of the Study:

• To develop a general prescription for calculating energy derivatives for rigid body systems.
• To improve the efficiency of geometry optimization techniques for coarse-grained models.
• To provide a flexible framework for various inter-body potentials and symmetries.

Main Methods:

• Utilizes an angle-axis representation for rigid-body rotational coordinates.
• Employs a matrix formulation for deriving first and second energy derivatives.
• Derives analytic expressions for Hessian eigenvectors for specific rotational cases.

Main Results:

• The matrix formulation significantly enhances geometry optimization performance (order of magnitude).
• Performance is comparable to methods exploiting specific molecular symmetry.
• Demonstrates flexibility in rapidly coding new site-site rigid-body potentials.

Conclusions:

• The proposed matrix formulation offers a powerful and efficient approach for rigid body geometry optimization.
• This method is applicable to diverse systems with various symmetries and potentials.
• Facilitates faster development and implementation of new molecular interaction models.