Theoretical Study on the Structure and Stabilities of Molecular Clusters of Oxalic Acid with Water

Abstract

The importance of aerosols to humankind is well-known, playing an integral role in determining Earth's climate and influencing human health. Despite this fact, much remains unknown about the initial events of nucleation. In this work, the molecular properties of common organic atmospheric pollutant oxalic acid and its gas phase interactions with water have been thoroughly examined. Local minima single-point energies for the monomer conformations were calculated at the B3LYP and MP2 level of theory with both 6-311++G(d,p) and aug-cc-pVDZ basis sets and are compared with previous works. Optimized geometries, relative energies, and free energy changes for the stable clusters of oxalic acid conformers with up to six waters were then obtained from B3LYP calculations with 6-31+G(d) and 6-311++G(d,p) basis sets. Initially, cooperative binding is predicted to be the most important factor in nucleation, but as the clusters grow, dipole cancellations are found to play a pivotal role. The clusters of oxalic acid hydrated purely with water tend to produce extremely stable and neutral core systems. Free energies of formation and atmospheric implications are discussed.

Understanding the catalytic role of oxalic acid in the SO<sub>3</sub> hydration to form H<sub>2</sub>SO<sub>4</sub> in the atmosphere

“…1993), is the water-soluble organic acid, so it has high concentration in aerosols (Kawamura et al, 2013;van Pinxteren et al, 2014;Deshmukh et al, 2016;Wang et al, 2016). In addition to accumulating in aerosols, oxalic acid, as an organic acid in the gas phase, has been found to enhance the new particle formation (NPF) (Xu et al, 2010;Weber et al, 2012;Xu and Zhang, 2012;Weber et al, 2014;Peng et al, 2015;Miao et al, 2015;Zhao et al, 2016;Chen et al, 2017;Xu et al, 2017;Arquero et al, 2017;Zhang, 2010). Theoretical studies about the effect of oxalic acid on atmospheric particle nucleation and growth have 5…”

“…shown that it can form stable complexes with water (Weber et al, 2012), sulfuric acid (Xu et al, 2010;Xu and Zhang, 2012;Miao et al, 2015;Zhao et al, 2016), ammonia (Weber et al, 2014;Peng et al, 2015) and amines (Chen et al, 2017;Xu et al, 2017;Arquero et al, 2017) via intermolecular hydrogen bond. The potential of oxalic acid for contributing to the NPF is mainly attributed to its capability of forming hydrogen bond with hydroxyl and/or carbonyl-type functional group.…”

Phosphoric acid – a potentially elusive participant in atmospheric new particle formation

“…Recent studies has shown that diamines clustering with sulfuric acid is an even more potent source of new particles than monoamines [25,26]. Highly oxidized organic molecules such as carboxylic acids [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] and products formed via autoxidation [43][44][45][46][47][48][49] has also been suggested to form clusters directly with sulfuric acid [50][51][52]. However, the volatility of autoxidation products might not be as low as initially assumed and there is still no conclusive evidence of their involvement in new particle formation [53,54].…”

Finding all‐nonmetal transition‐metal‐like superatom and its magnetic building block

“…The fracture energy ( E f ) of a B atom out of B 6 framework was computed with the counterpoise procedure to eliminate the basis set superposition error (BSSE), the E f is defined as …”