TY - JOUR

T1 - Theoretical and Numerical Comparison of Quantum- and Classical Embedding Models for Optical Spectra

AU - Jansen, Marina

AU - Reinholdt, Peter

AU - Hedegård, Erik Donovan

AU - König, Carolin

N1 - This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) through the Emmy Noether Young Group Leader Programme (project KO 5423/1-1). EDH thanks The Villum Foundation, Young Investigator Program (grant no. 29412), the Swedish Research Council (grant no. 2019-04205), and Independent Research Fund Denmark (grant no. 0252-00002B and grant no. 2064-00002B) for support. The computations were carried out on the cluster system at the Leibniz University Hannover, Germany, which is funded by the Leibniz University Hannover, the Lower Saxony Ministry of Science and Culture (MWK) and the DFG.

PY - 2023/7/13

Y1 - 2023/7/13

N2 - Quantum-mechanical (QM) and classical embedding models approximate a supermolecular quantum-chemical calculation. This is particularly useful when the supermolecular calculation has a size that is out of reach for present QM models. Although QM and classical embedding methods share the same goal, they approach this goal from different starting points. In this study, we compare the polarizable embedding (PE) and frozen-density embedding (FDE) models. The former is a classical embedding model, whereas the latter is a density-based QM embedding model. Our comparison focuses on solvent effects on optical spectra of solutes. This is a typical scenario where super-system calculations including the solvent environment become prohibitively large. We formulate a common theoretical framework for PE and FDE models and systematically investigate how PE and FDE approximate solvent effects. Generally, differences are found to be small, except in cases where electron spill-out becomes problematic in the classical frameworks. In these cases, however, atomic pseudopotentials can reduce the electron-spill-out issue.

AB - Quantum-mechanical (QM) and classical embedding models approximate a supermolecular quantum-chemical calculation. This is particularly useful when the supermolecular calculation has a size that is out of reach for present QM models. Although QM and classical embedding methods share the same goal, they approach this goal from different starting points. In this study, we compare the polarizable embedding (PE) and frozen-density embedding (FDE) models. The former is a classical embedding model, whereas the latter is a density-based QM embedding model. Our comparison focuses on solvent effects on optical spectra of solutes. This is a typical scenario where super-system calculations including the solvent environment become prohibitively large. We formulate a common theoretical framework for PE and FDE models and systematically investigate how PE and FDE approximate solvent effects. Generally, differences are found to be small, except in cases where electron spill-out becomes problematic in the classical frameworks. In these cases, however, atomic pseudopotentials can reduce the electron-spill-out issue.

UR - http://www.scopus.com/inward/record.url?scp=85164624706&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2304.11682

DO - 10.48550/arXiv.2304.11682

M3 - Article

VL - 127

SP - 5689

EP - 5703

JO - The Journal of Physical Chemistry A

JF - The Journal of Physical Chemistry A

SN - 1089-5639

IS - 27

ER -