Quasi-Particle Self-Consistent GW for Molecules.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Accurate prediction of electronic properties is crucial for designing new materials, particularly in organic photovoltaics.
• Traditional methods like G0W0 approximations have limitations in capturing self-consistency effects.
• Quasi-particle self-consistent GW (qsGW) methods offer a more rigorous approach to electronic structure calculations.

Purpose of the Study:

• To present the formalism and implementation of quasi-particle self-consistent GW (qsGW) and eigenvalue-only GW (evGW) methods within standard quantum chemistry packages.
• To benchmark the accuracy of qsGW and evGW against high-level coupled-cluster theory and experimental data.
• To compare qsGW with self-consistent GW (scGW) for organic photovoltaic molecules and assess the impact of self-consistency on ground-state properties.

Main Methods:

• Developed and integrated qsGW and evGW formalisms into widely used quantum chemistry software.
• Benchmarked the methods using a diverse set of molecules, comparing results with coupled-cluster computations and experimental measurements.
• Investigated the effect of self-consistency on ground-state density by comparing calculated and experimental dipole moments for organic photovoltaic materials.

Main Results:

• The qsGW approach demonstrates significant improvements in accuracy compared to the conventional G0W0 approximation.
• Partially self-consistent methods, particularly evGW, show promise as computationally efficient yet accurate alternatives.
• Analysis of dipole moments confirms the importance of self-consistency for accurately describing ground-state electronic properties.

Conclusions:

• qsGW provides a substantial advancement over G0W0 for calculating electronic properties of molecules.
• evGW emerges as a highly effective and computationally feasible alternative to full qsGW.
• The implemented methods offer reliable tools for electronic structure calculations in computational chemistry and materials science.