Geometry optimization made simple with translation and rotation coordinates.

Area of Science:

• Computational chemistry
• Molecular modeling
• Theoretical physics

Background:

• Accurate molecular geometry is crucial for understanding intermolecular interactions.
• Existing coordinate systems may not fully capture collective molecular motions.

Purpose of the Study:

• To introduce a novel coordinate system, translation-rotation-internal coordinate (TRIC), for molecular geometry.
• To improve the efficiency and accuracy of theoretical studies on intermolecular interactions.

Main Methods:

• Developed the TRIC system incorporating collective translations and rotations.
• Utilized centroid position for translations and quaternion-based exponential map for orientations.
• Integrated TRIC into geometry optimization calculations.
• Introduced a new method for scanning molecular orientations.

Main Results:

• TRIC demonstrated superior performance over existing systems in geometry optimization.
• Consistent improvements were observed across diverse systems like water clusters and organic complexes.
• The method facilitates exploration of potential energy surfaces by allowing orthogonal degrees of freedom to relax.

Conclusions:

• The TRIC system offers a more natural and effective approach to describing molecular geometry, especially for systems with significant intermolecular interactions.
• Explicitly including molecular translation and rotation is key to navigating complex potential energy surfaces.