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Abstract

In this work, we present a detailed comparison between wavefunction-based and particle/hole techniques for the prediction of band gap energies of
semiconductors. We focus on the comparison of the back-transformed Pair Natural
Orbital Similarity Transformed Equation of Motion Coupled-Cluster (bt-PNOSTEOM-CCSD) method with Time Dependent Density Functional Theory (TDDFT) and Delta Self Consistent Field/DFT (Δ-SCF/DFT) that are employed to
calculate the band gap energies in a test set of organic and inorganic semiconductors.
Throughout, we have used cluster models for the calculations that were calibrated by
comparing the results of the cluster calculations to periodic DFT calculations with the
same functional. These calibrations were run with cluster models of increasing size
until the results agreed closely with the periodic calculation. It is demonstrated that
bt-PNO-STEOM-CC yields accurate results that are in better than 0.2 eV agreement
with the experiment. This holds for both organic and inorganic semiconductors. The
efficiency of the employed computational protocols is thoroughly discussed. Overall,
we believe that this study is an important contribution that can aid future developments and applications of excited state
coupled cluster methods in the field of solid-state chemistry and heterogeneous catalysis.