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

## TL;DR

This paper introduces new Gaussian basis sets for accurate and efficient excited-state calculations on large molecules.

## Contribution

The novel contribution is the development of augmented MOLOPT basis sets optimized for excited-state calculations.

## Key findings

- Augmented MOLOPT basis sets achieve fast convergence of GW gaps and excitation energies.
- The double-ζ basis has a 60 meV mean absolute deviation for GW HOMO–LUMO gaps.
- GW calculations on large nanographenes are feasible with low computational resources.

## Abstract

We introduce a family of all-electron Gaussian basis
sets, augmented
MOLOPT, optimized for excited-state calculations on large molecules.
We generate these basis sets by augmenting existing STO-3G, STO-6G,
and MOLOPT basis sets optimized for ground state energy calculations.
The augmented MOLOPT basis sets achieve fast convergence of GW gaps and Bethe–Salpeter excitation energies, while
maintaining low condition numbers of the overlap matrix to ensure
numerical stability. For GW HOMO–LUMO gaps,
the double-ζ augmented MOLOPT basis yields a mean absolute deviation
of 60 meV to the complete basis set limit. The basis set convergence
for excitation energies from time-dependent density functional theory
and the Bethe–Salpeter equation is similar. We use our smallest
generated augmented MOLOPT basis (aug-SZV-MOLOPT-ae-mini) to demonstrate GW calculations on nanographenes with 9224 atoms requiring
only 34300 core hours of computational resources.