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DOE OSTI · 1802803

A zeroth-order active-space frozen-orbital embedding scheme for multireference calculations

He, Nan·Evangelista, Francesco A.
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Abstract

Multireference computations of large-scale chemical systems are typically limited by the computational cost of quantum chemistry methods. In this work, we develop a zeroth-order active space embedding theory [ASET(0)], a simple and automatic approach for embedding any multireference dynamical correlation method based on a frozen-orbital treatment of the environment. ASET(0) is combined with the second-order multireference driven similarity renormalization group and tested on several benchmark problems, including the excitation energy of 1-octene and bond-breaking in ethane and pentyldiazene. Finally, we apply ASET(0) to study the singlet–triplet gap of p-benzyne and 9,10-anthracyne diradicals adsorbed on a NaCl surface. Our results show that despite its simplicity, ASET(0) is a powerful and sufficiently accurate embedding scheme applicable when the coupling between the fragment and the environment is in the weak to medium regime.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYAdsorptionChemistryDynamical correlationElectrostaticsExcitation energiesFree radicalsOrganic compoundsPerturbation theoryPhysicsQuantum chemistryRenormalization and regularization

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He, Nan, Evangelista, Francesco A.. 2020-03-03. A zeroth-order active-space frozen-orbital embedding scheme for multireference calculations. https://doi.org/10.1063/1.5142481

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