Gaussian Basis Sets for All-Electron Excited-State Calculations of Large Molecules

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Accurate excited-state calculations are crucial for understanding molecular properties.
• Existing basis sets often struggle with convergence and numerical stability for large systems.
• Optimizing basis sets for excited-state calculations is computationally demanding.

Purpose of the Study:

• Introduce a new family of all-electron Gaussian basis sets, augmented MOLOPT.
• Optimize these basis sets for efficient and accurate excited-state calculations on large molecules.
• Ensure numerical stability and fast convergence for electronic property predictions.

Main Methods:

• Augmenting existing ground-state optimized basis sets (STO-3G, STO-6G, MOLOPT).
• Evaluating convergence of GW gaps and Bethe-Salpeter excitation energies.
• Assessing numerical stability via overlap matrix condition numbers.

Main Results:

• Augmented MOLOPT basis sets show fast convergence for GW gaps and Bethe-Salpeter excitation energies.
• The double-ζ augmented MOLOPT basis achieves a 60 meV MAD to the complete basis set limit for GW HOMO-LUMO gaps.
• Basis set convergence is comparable for time-dependent density functional theory and Bethe-Salpeter equation methods.
• Demonstrated GW calculations on large nanographenes (9224 atoms) using the smallest augmented basis set (aug-SZV-MOLOPT-ae-mini) with 34300 core hours.

Conclusions:

• The augmented MOLOPT basis sets offer a significant advancement for excited-state calculations.
• These basis sets provide a balance of accuracy, efficiency, and numerical stability.
• Enables large-scale GW and Bethe-Salpeter equation calculations on complex molecular systems.