Semiempirical Quantum-Chemical Methods with Orthogonalization and Dispersion Corrections.

Area of Science:

• Computational chemistry
• Quantum chemistry

Background:

• Semiempirical quantum-chemical methods are essential for molecular modeling.
• Existing methods like MNDO-type and OM x have limitations in accuracy.
• Accurate description of dispersion interactions and thermal effects is crucial.

Purpose of the Study:

• To introduce two novel semiempirical quantum-chemical methods, ODM2 and ODM3 (ODM x).
• To enhance the accuracy of predicting ground-state and excited-state properties.
• To improve the description of noncovalent interactions.

Main Methods:

• Development of ODM2 and ODM3 methods based on OM2 and OM3 electronic structure models.
• Incorporation of Grimme's dispersion correction D3 with Becke-Johnson damping.
• Inclusion of three-body corrections (E^ABC) for Axilrod-Teller-Muto interactions.
• Explicit computation of zero-point vibrational energy and thermal corrections for heats of formation.
• Optimization of parameters for H, C, N, O, and F using state-of-the-art reference data.

Main Results:

• ODM x methods demonstrate superior performance compared to MNDO-type and OM x methods for ground-state and excited-state properties.
• Noncovalent interactions are described with accuracy comparable to OM x methods using post-hoc dispersion corrections.
• Optimized parameters cover key elements relevant to organic and medicinal chemistry.

Conclusions:

• ODM x methods represent a significant advancement in semiempirical quantum chemistry.
• These methods provide a more accurate and efficient approach for molecular property prediction.
• The inclusion of dispersion and thermal corrections enhances predictive power for diverse chemical systems.