Assessment of the Linearized GW Density Matrix for Molecules

Area of Science:

• Quantum chemistry
• Computational physics
• Materials science

Background:

• The GW approximation is a powerful tool for calculating ionization potentials and electron affinities.
• The Green's function in GW calculations contains more information than just quasi-particle energies.
• A linearized GW density matrix has been proposed to capture additional significant Feynman diagrams.

Purpose of the Study:

• To assess the quality of the linearized GW density matrix for molecular properties.
• To extend the linearization method to start from various mean-field approximations.
• To evaluate the reliability and stability of the linearized GW density matrix for total energy calculations.

Main Methods:

• Extending the linearization formulation to arbitrary self-consistent mean-field starting points.
• Performing non-self-consistent GW calculations using the linearized density matrix.
• Benchmarking against established techniques for electronic density, Hartree energy, exchange energy, and Fock operator expectation values.

Main Results:

• Demonstrated the reliability and stability of the linearized GW density matrix for total energy evaluation.
• Showcased significant differences between linearized GW densities and those from quasi-particle self-consistent GW.
• Provided a comprehensive comparison of molecular properties across 34 molecules.

Conclusions:

• The linearized GW density matrix is a valuable tool for calculating molecular properties beyond quasi-particle energies.
• This method offers an alternative to the quasi-particle self-consistent GW approximation with distinct results.
• The extended formulation allows for greater flexibility in applying the linearized GW approach.