Water dimer isomers: interaction energies and electronic structure

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Water dimer isomers represent fundamental hydrogen-bonded systems.
• Understanding their energetic and electronic properties is crucial for solvation and atmospheric chemistry.

Purpose of the Study:

• To investigate the energetic and electronic structure of various water dimer isomers.
• To categorize and compare different dimer topologies (linear, ring, bifurcated) and geometries (planar, non-planar).

Main Methods:

• Density Functional Theory (DFT) methodology was employed.
• Bader's Atoms in Molecules (AIM) theory was utilized.
• Reduced Density Gradient (RDG) and Non-Covalent Interaction (NCI) analyses were performed.

Main Results:

• Six distinct water dimer isomers were identified, categorized as planar and non-planar.
• Linear dimers exhibited the highest interaction energy, followed by ring and then bifurcated dimers.
• Planar dimers had slightly higher energies than their non-planar counterparts within each topology.

Conclusions:

• The electronic structure and electron density distribution correlate with the interaction energies of water dimer isomers.
• AIM, RDG, and NCI analyses provide insights into the nature of hydrogen bonding in water dimers.