Improving half-projected spin-contaminated wave functions by multi-configuration perturbation theory.

Area of Science:

• Quantum chemistry
• Computational physics

Background:

• Spin-contaminated wave functions can arise in geminal methods.
• Spin-projection techniques, like half-projection, mitigate contamination but can affect size consistency.

Purpose of the Study:

• To improve half-projected spin-contaminated geminal wave functions.
• To incorporate dynamical correlation effects into these wave functions.

Main Methods:

• Utilizing multi-configuration perturbation theory.
• Applying it to half-projected spin-contaminated geminal wave functions.

Main Results:

• The study investigates the effectiveness of multi-configuration perturbation theory in this context.
• It aims to quantify the improvement in describing dynamical correlation.

Conclusions:

• Multi-configuration perturbation theory offers a pathway to enhance half-projected geminal wave functions.
• This approach seeks to balance spin-purity and size consistency while including electron correlation.