Robust Analytic-Continuation Approach to Many-Body GW Calculations

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Analytic continuation of the GW self-energy to the real-energy axis presents a significant challenge in electronic structure calculations.
• Exploiting response functions at imaginary frequencies offers computational advantages but requires overcoming this analytic continuation hurdle.
• Accurate calculation of electronic properties, especially for states far from the Fermi level, remains an active area of research.

Purpose of the Study:

• To develop and validate a superior method for the analytic continuation of electronic self-energy calculations.
• To compare the analytic continuation of the dynamically screened-Coulomb potential (W) versus the GW self-energy operator.
• To extend the analytic continuation scheme to accurately describe core states and states far from the band gap, incorporating quasiparticle lifetimes.

Main Methods:

• Integration of contour-deformation and analytic-continuation techniques into a unified computational scheme.
• Extensive calculations performed on large sets of molecules to ensure robustness and general applicability.
• Generalization of the analytic continuation method to account for quasiparticle lifetimes and extended energy ranges.

Main Results:

• Demonstrated that analytic continuation of the dynamically screened-Coulomb potential (W) is computationally preferable to continuing the GW self-energy.
• Extensive molecular calculations confirm the improved accuracy and efficiency of continuing W.
• The generalized scheme accurately handles states distant from the band gap, including core electronic states.

Conclusions:

• Analytically continuing the screened Coulomb potential (W) offers a more practical and accurate approach for real-energy GW calculations.
• The developed method provides a robust framework for electronic structure calculations across a wide range of molecular systems and electronic states.
• Incorporating quasiparticle lifetimes significantly enhances the description of electronic properties, particularly for core and deep-lying states.