A correlation-relaxation-balanced direct method at the second order perturbation theory for accurate ionization...

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Accurate prediction of ionization potential (IP) spectra is crucial in quantum chemistry.
• Existing methods often struggle with efficiency or accuracy across valence and core electrons.

Purpose of the Study:

• To develop a quasi-particle approach for efficient and accurate prediction of complete ionization potential (IP) spectra.
• To establish a direct method for calculating IP spectra from valence to core electrons.

Main Methods:

• Developed a correlation-relaxation-balanced direct method, CRB-MP2.
• Utilized a parameter-scaled scheme of two-particle, one-hole (2ph) and two-hole, one-particle (2hp) summation terms.
• Based on second-order perturbation theory, incorporating electron correlation and relaxation effects.

Main Results:

• The CRB-MP2 method achieves high-quality valence and core IPs.
• The method demonstrates accuracy and efficiency for a wide range of species.
• Achieved almost no extra computational cost beyond a standard MP2 calculation.

Conclusions:

• Established a direct, accurate, and efficient approach for complete IP spectrum calculations.
• CRB-MP2 offers a significant advancement in predicting electronic excitation energies.
• The method provides a valuable tool for quantum chemistry research.