GW100: A Plane Wave Perspective for Small Molecules.

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Mechanics

Background:

• Previous G0W0 studies using Gaussian basis sets demonstrated high accuracy for molecular electronic properties.
• The projector augmented wave (PAW) method and Vienna ab initio simulation package (VASP) offer an alternative computational approach.

Purpose of the Study:

• To compare the accuracy of the PAW method with VASP against established Gaussian basis set calculations for molecular electronic properties.
• To assess the performance of VASP for ionization potentials, electron affinities, and quasiparticle resonances.

Main Methods:

• Utilized the projector augmented wave (PAW) method within the Vienna ab initio simulation package (VASP).
• Performed calculations on 100 closed-shell molecules previously studied with Gaussian basis sets.
• Applied corrections for finite basis set errors and periodic image interactions.

Main Results:

• VASP calculations showed excellent agreement (<50 meV) with Gaussian basis sets for ionization potentials after basis set extrapolation and corrections.
• Slightly larger discrepancies were observed for positive electron affinities, attributed to Gaussian basis set extrapolation errors.
• Substantial differences were found for quasiparticle resonances above the vacuum level, potentially due to incomplete convergence in Gaussian basis set calculations.

Conclusions:

• The PAW method implemented in VASP provides accurate results for ionization potentials and electron affinities, comparable to Gaussian basis set methods.
• Further investigation is needed to address the discrepancies in quasiparticle resonance calculations, possibly related to basis set convergence in Gaussian-type orbital methods.