Core-Level Binding Energies from GW: An Efficient Full-Frequency Approach within a Localized Basis

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Spectroscopy

Background:

• The GW method is standard for predicting charged valence excitations.
• Existing efficient GW algorithms fail for core excitations, limiting X-ray photoelectron spectroscopy (XPS) analysis.
• Core-level calculations require specialized numerical techniques due to complex self-energy pole structures.

Purpose of the Study:

• To develop a robust GW method capable of accurately computing core-level excitations.
• To enable precise calculations of core-level binding energies for molecules and solids.
• To provide a more accurate alternative to existing methods like delta self-consistent field (ΔSCF).

Main Methods:

• A full-frequency approach on the real axis using a localized basis set.
• Implementation of the contour deformation technique for efficient self-energy calculation.
• Validation against a fully analytic GW algorithm and experimental data.

Main Results:

• The developed GW method successfully treats core levels, overcoming limitations of previous algorithms.
• Calculated core-level binding energies for small molecules and polycyclic hydrocarbons show deviations under 0.5 eV from experimental values.
• The method demonstrates high accuracy compared to density functional theory (DFT)-based approaches.

Conclusions:

• The new GW method provides accurate and efficient calculations of core-level binding energies.
• This advancement extends the applicability of GW theory to core-level spectroscopy (XPS).
• The massively parallel implementation supports computations for systems up to 100 atoms.