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arXiv · 2501.18667

Exploring the accuracy of the equation-of-motion coupled-cluster band gap of solids

Evgeny Moerman·Henrique Miranda·Alejandro Gallo·Andreas Irmler·Tobias Schäfer·Felix Hummel·Manuel Engel·Georg Kresse·Matthias Scheffler·Andreas Grüneis
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Abstract

While the periodic equation-of-motion coupled-cluster (EOM-CC) method promises systematic improvement of electronic band gap calculations in solids, its practical application at the singles and doubles level (EOM-CCSD) is hindered by severe finite-size errors in feasible simulation cells. We present a hybrid approach combining EOM-CCSD with the computationally efficient $GW$ approximation to estimate thermodynamic limit band gaps for several insulators and semiconductors. Our method substantially reduces required cell sizes while maintaining accuracy. Comparisons with experimental gaps and self-consistent $GW$ calculations reveal that deviations in EOM-CCSD predictions correlate with reduced single excitation character of the excited many-electron states. Our work not only provides a computationally tractable approach to EOM-CC calculations in solids but also reveals fundamental insights into the role of single excitations in electronic-structure theory.

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Evgeny Moerman, Henrique Miranda, Alejandro Gallo, Andreas Irmler, Tobias Schäfer, Felix Hummel, Manuel Engel, Georg Kresse, Matthias Scheffler, Andreas Grüneis. 2025-01-30. Exploring the accuracy of the equation-of-motion coupled-cluster band gap of solids. https://arxiv.org/abs/2501.18667

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