Visualizing internal stabilization in weakly bound systems using atomic energies: hydrogen bonding in small water...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Understanding the energetic contributions within molecular clusters is crucial for comprehending their properties.
• The quantum theory of atoms in molecules (QTAIM) provides a framework for analyzing electron distribution and atomic properties.
• Previous studies have explored water cluster stability, but atomic-level energy visualization remains an area for development.

Purpose of the Study:

• To develop and apply a method for visualizing local stabilizing and destabilizing energy changes in water clusters at the atomic level.
• To investigate the energetic contributions of individual atoms (oxygen and hydrogen) within small water clusters.
• To correlate atomic energy variations with hydrogen bond strengths and cooperativity.

Main Methods:

• Utilized atomic energies derived from the quantum theory of atoms in molecules (QTAIM).
• Calculated energies for small water clusters ((H2O)n, n=2-5) using MP2/aug-cc-pVTZ geometries.
• Correlated atomic energy variations with cluster geometry and hydrogen bond characteristics.

Main Results:

• Atomic energies accurately reproduced MP2 total energies for the water clusters.
• Oxygen atoms were consistently stabilized, while hydrogen atoms were destabilized across all studied clusters.
• Demonstrated atomic-level evidence of hydrogen bond cooperativity contributing to cluster stability.
• Observed correlations between atomic energy variations and local geometry, indicating differences in hydrogen bond strengths.

Conclusions:

• Atomic energy visualization provides a powerful tool for understanding energetic contributions in molecular systems.
• The method effectively illustrates hydrogen bond cooperativity and variations in bond strength within water clusters.
• This approach is highly suitable for analyzing energy changes in larger, more complex systems like biomolecules.