Electronic Excitation Energies and Ionization Potentials with Sub-Chemical Accuracy from EOM-CC Composite Methods

Key Points

• The aim is to evaluate how electron correlation affects the accuracy of excitation energies and ionization potentials using EOM-CC methods.
• Utilized EOM-CC composite methods to calculate excitation energies and ionization potentials
• Assessed the convergence rate of EOM-CC compared to ground-state coupled cluster methods
• Achieved sub-chemical accuracy for excitation energies and ionization potentials
• Found slower convergence to the full configuration interaction limit with EOM-CC methods compared to ground-state methods