Density functional theory and the correlation consistent basis sets: the tight d effect on HSO and HOS

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• The study of HSO and HOS isomers is crucial for understanding chemical reactivity and reaction pathways.
• Previous theoretical studies have employed various Density Functional Theory (DFT) functionals and basis sets with varying degrees of accuracy.

Purpose of the Study:

• To accurately determine the structures, relative energies, and isomerization barriers of HSO and HOS isomers.
• To evaluate the performance of DFT functionals (B3LYP, B3PW91, PBE) with tight d-augmented correlation consistent basis sets.
• To compare new computational results with existing ab initio and DFT data.

Main Methods:

• Utilized DFT functionals (B3LYP, B3PW91, PBE) with tight d-augmented correlation consistent basis sets (cc-pV(x+d)Z, aug-cc-pV(x+d)Z).
• Calculated molecular structures, vibrationally averaged structures, relative energies, harmonic and anharmonic frequencies, and enthalpies of formation.
• Determined the isomerization barrier between HSO and HOS.

Main Results:

• Tight d-augmented basis sets show faster and smoother convergence for relative energies compared to standard basis sets.
• The B3PW91/aug-cc-pV(5+d)Z calculations provide relative energy results in excellent agreement with CCSD(T) data.
• Accurate structural and energetic parameters for both HSO and HOS isomers were obtained.

Conclusions:

• The use of tight d-augmented basis sets significantly improves the reliability of DFT calculations for HSO and HOS isomers.
• The B3PW91 functional with the aug-cc-pV(5+d)Z basis set is recommended for future studies of these systems.
• This work provides highly accurate computational data for HSO and HOS, aiding further theoretical and experimental investigations.