From simple molecules to nanotubes. Reliable predictions of ionization potentials from the ΔMP2-SCS methods

The vertical ionization potentials for systems of various sizes, ranging from simple molecules, DNA/RNA bases, donor and acceptor organic molecular systems as well as nanotubes are calculated using the ΔMP2-SCS family of methods [Śmiga et al 2018 J. Chem. Theory Comput. 14 4780–90]. We have shown that for all investigated cases, the ΔMP2-SCS methods, being almost cost free single-step post-Hartree–Fock calculation, provide very accurate vertical ionization potentials comparable in quality with state-of-art outer valence Green's function methods. Moreover, we show that a combination of the ΔMP2-SCS methods with the resolution of identity technique is effective and reliable an alternative to the semi-empirical density functional theory methods and Green's function-based calculations of ionization potentials for large molecular systems such as silicon-based or organic-based solar cells, for which the IP-EOM-CCSD calculations are too expensive for routine calculations. (paper)