Correcting Basis Set Incompleteness in Wave Function Correlation Energy by Dressing Electronic Hamiltonian with an...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Basis set incompleteness is a significant error source in electronic structure calculations.
• Accurate computation of electron correlation energy is crucial for predicting molecular properties.

Purpose of the Study:

• To develop a general and efficient method for reducing basis set incompleteness error in electron correlation energy calculations.
• To introduce a novel approach that computes corrections within a single calculation.

Main Methods:

• Modification of the electron interaction operator with an effective short-range interaction.
• Local mapping of the Coulomb operator to a long-range interaction using a range-separated parameter.
• Application with complete active space wave functions and linearized adiabatic connection (AC0) or n-electron valence state second-order perturbation theory (NEVPT2).

Main Results:

• The proposed method effectively reduces basis set incompleteness error.
• Calculations in a triple-ζ basis set achieved accuracy comparable to or exceeding uncorrected methods in a quintuple-ζ basis set.
• Encouraging results were obtained for the relative energies of test molecules.

Conclusions:

• The developed approach offers a computationally efficient way to improve the accuracy of electron correlation energy calculations.
• This method provides a viable alternative to traditional basis set extrapolation or augmentation techniques.
• The findings suggest a significant advancement in achieving high-accuracy electronic structure calculations with reduced computational cost.