MP2.X: a generalized MP2.5 method that produces improved binding energies with smaller basis sets

Area of Science:

• Computational chemistry
• Quantum chemistry

Background:

• Accurate calculation of binding energies is crucial for understanding molecular interactions.
• The MP2.5 method offers a correction to MP2, but its performance can vary with basis sets.

Purpose of the Study:

• To evaluate the performance of a scaled MP2.5 method (MP2.X) for calculating binding energies.
• To assess the accuracy of MP2.X across different basis sets using the S66 dataset.

Main Methods:

• The study employed a scaled MP2.5 (MP2.X) method.
• Calculations were performed using various basis sets, including 6-31G*, 6-311++G**, aug-cc-pVDZ, and aug-cc-pVTZ.
• Results were compared against the S66 dataset for interaction energies.

Main Results:

• Scaling the MP2.5 correction term significantly improved binding energies, especially for smaller basis sets.
• The MP2.X method achieved low Root Mean Square (RMS) errors of approximately 0.15 kcal/mol for all tested basis sets.
• MP2.X provided a more balanced description of noncovalent interactions compared to MP2.5, particularly for dispersion-bound and mixed complexes.

Conclusions:

• The MP2.X method represents a significant improvement over MP2.5 for calculating binding energies.
• MP2.X demonstrates robust accuracy and a balanced treatment of noncovalent interactions across a range of basis sets.
• This scaled method is a valuable tool for computational studies of molecular interactions.