Modeling Goldberg polyhedral like water nanobubbles structure stability using density functional theory*

Water nanobubbles persist in their environment for extended periods. However, according to the Epstein and Plesset theory, their lifetimes should be short, suggesting thermodynamic instability. Although continuum theories have attempted to explain their stability, they lack empirical evidence. To address this issue, we propose a molecular model of water nanobubbles based on Goldberg polyhedral structures (GP) and examine their stability using density functional theory (DFT). Due to the higher number of hydrogens than edges in the GP, we have multiple configurations for each GP. We hypothesize that the most stable configurations are the "least polar" structures, where the distribution of free H atoms around the GP is uniform. We implemented an algorithm to produce the least polar atomistic configurations, and then we used geometric optimization (GO) techniques to minimize the energy of these structures under various conditions in order to verify the stability of our structures and their suitability as a model for water nanobubbles. GO were conducted under isolation, solvent effects using COSMO, and immersion in an explicit solvent (water). This was applied to water structures with GP(1,0), GP(1,1), and GP(2,0) geometries. Additionally, we evaluated the influence of hydrogen configuration by constructing more polar structures and comparing parameters such as total energy, HOMO-LUMO gap, and dipole moment. Our analysis revealed that structures in the least polar configuration remained stable without bond breakage after GO, even under different solvent conditions, suggesting that our model is an effective representation of small water nanobubbles. Furthermore, our research highlighted the influence of hydrogen atom configuration on structural stability. We also observed changes in HOMO and LUMO orbitals between the least polar and other configurations, particularly in proximity to neighboring free hydrogen atoms. This phenomenon was reflected in the dipole moment, which increased with a greater number of adjacent free hydrogen atoms. Consequently, structures with higher dipole moments exhibited bond breakage after GO, highlighting the influence of polarity on the stability of our proposed structures.