Monohydrated Sulfuric and Phosphoric Acids with Different Hydrogen Atom Orientations: DFT and Ab initio Study

Bulletin of the Korean chemical society

Maciej Ko aski¹  Seung Joo Cho¹ 

关键词: Monohydrated sulfuric and phosphoric acids;    Density functional theory;    Harmonic vibrational frequencies;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

We carried out DFT calculations for monohydrated sulfuric and phosphoric acids. We are interested in clusters which differ in orientation of hydrogen atoms only. Such molecular complexes are close in energy, since they lie in the vicinity of the global minimum energy structure on the flat potential energy surface. For monohydrated sulfuric acid we identified four different isomers. The monohydrated phosphoric acid forms five different conformers. These systems are difficult to study from the theoretical point of view, since binding energy differences in several cases are very small. For each structure, we calculated harmonic vibrational frequencies to be sure that if the optimized structures are at the local or global minima on the potential energy surface. The analysis of calculated –OH vibrational frequencies is useful in interpretation of infrared photodissociation spectroscopy experiments. We employed four different DFT functionals in our calculations. For each structure, we calculated binding energies, thermodynamic properties, and harmonic vibrational frequencies. Our analysis clearly shows that DFT approach is suitable for studying monohydrated inorganic acids with different hydrogen atom orientations. We carried out MP2 calculations with aug-cc-pVDZ basis set for both monohydrated acids. MP2 results serve as a benchmark for DFT calculations.

【 授权许可】

Unknown