A scaled explicitly correlated F12 correction to second-order Møller-Plesset perturbation theory

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Second-order Møller-Plesset perturbation theory (MP2) is a standard method for calculating electron correlation.
• Explicitly correlated F12 methods enhance MP2 accuracy but are computationally expensive.
• Accurate calculation of interaction energies is crucial for understanding molecular interactions.

Purpose of the Study:

• To introduce an empirically scaled version of the MP2-F12 method.
• To reduce the computational cost of F12 corrections while preserving accuracy.
• To provide a computationally efficient yet accurate method for interaction energy calculations.

Main Methods:

• Developed an empirically scaled MP2-F12 correction.
• Determined basis set-dependent scaling factors by fitting to the S66 molecular complex set.
• Validated the scaled method on the S22 and L7 test sets.

Main Results:

• The scaled MP2-F12 method accurately reproduces unscaled F12 interaction energy corrections.
• Achieved mean percentage errors below 1% for F12 corrections and negligible errors (<0.01 kcal mol⁻¹) for total interaction energies on test sets.
• Demonstrated significant computational speedups compared to the unscaled F12 correction, especially for larger systems.

Conclusions:

• The empirically scaled MP2-F12 method offers a highly accurate and computationally efficient alternative for interaction energy calculations.
• This method significantly reduces the cost associated with explicit correlation terms.
• The approach is broadly applicable and provides negligible errors for second-order perturbation theory methods.