The LDA-1/2 Method Applied to Atoms and Molecules.

Area of Science:

• Computational chemistry
• Condensed matter physics

Background:

• The LDA-1/2 method approximates ionization potentials using highest occupied molecular orbital (HOMO) energies at half occupation.
• This method has shown promise for calculating semiconductor band gaps.

Purpose of the Study:

• To assess the accuracy of the LDA-1/2 method for finite systems, specifically atoms and molecules.
• To compare LDA-1/2 performance against established methods like CCSD(T) and G0W0.
• To analyze the underlying assumptions and limitations of the LDA-1/2 methodology.

Main Methods:

• Application of the LDA-1/2 method to the GW100 test set of atoms and molecules.
• Validation of calculated HOMO energies against coupled cluster singles, doubles, and perturbative triples (CCSD(T)) data.
• Comparison with the G0W0 Green's function approach within many-body perturbation theory.

Main Results:

• LDA-1/2 demonstrates comparable accuracy to the G0W0 method for ionization potentials in finite systems.
• The G0W0 approach, while accurate, is significantly more computationally demanding.
• Analysis provides insights into the strengths and weaknesses inherent in the LDA-1/2 assumptions.

Conclusions:

• LDA-1/2 offers a computationally efficient and accurate alternative for calculating ionization potentials and band gaps.
• The method's viability is confirmed for finite systems, matching high-level theoretical approaches.
• Understanding the method's assumptions is key to its optimal application in electronic structure calculations.