Equilibrium structure of sulfuric acid.

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• Sulfuric acid (H2SO4) is a crucial industrial chemical.
• Accurate molecular structures and spectroscopic data are essential for understanding its properties and reactivity.

Purpose of the Study:

• To determine the precise equilibrium structure of the more stable C2 conformer of H2SO4.
• To calculate accurate spectroscopic constants and vibrational properties.
• To refine the ab initio calculated structure using experimental data.

Main Methods:

• Ab initio calculations using the Coupled Cluster Singles Doubles with Perturbative Triples (CCSD(T)) method.
• Calculation of quadratic, cubic, and quartic force fields at the MP2 level of theory.
• Determination of semiexperimental equilibrium rotational constants.

Main Results:

• The equilibrium structure of H2SO4 was accurately determined.
• Spectroscopic constants derived from the calculated force field showed satisfactory agreement with experimental values.
• The ab initio structure was refined using a mixed regression method based on semiexperimental rotational constants.

Conclusions:

• The study provides a highly accurate equilibrium structure for H2SO4.
• The calculated spectroscopic data are reliable and consistent with experimental observations.
• The methodology allows for the refinement of theoretical structures using experimental spectroscopic data.