Abstract
In this work we present the first implementation of the incremental scheme for coupled cluster linear-response frequency-dependent dipole polarizabilities. The implementation is fully automated and makes use of the domain-specific basis set approach. The accuracy of the approach is determined on the basis of a test suite of 47 molecules and small clusters. The local approximation in the coupled cluster singles and doubles polarizability exhibits a mean error of 0.02% and a standard deviation of 0.32% when using a third-order incremental expansion. With the proposed approach, it is possible to compute polarizabilities with larger basis sets compared to the canonical implementation and thus it is possible to obtain higher total accuracy. The incremental scheme yields the smallest errors for weakly-bound and quasi-linear systems, while two- and three-dimensional (cage-like) structures exhibit somewhat larger errors as compared to the full test set.
Highlights
Quantum chemical methods such as coupled cluster theory[1,2,3,4] can provide robust and reliable simulations of both resonant and non-resonant interactions of molecules with electric and magnetic fields.[5]
The coupled cluster singles and doubles (CCSD) method,[6] as well as CCSD augmented with approximate triples [e.g., CCSD(T) or CC3],7,8 have been found to provide very high accuracy in simulations of UV/vis[9,10,11,12,13,14] and circular dichroism spectra[15,16,17,18,19] as well as dipolepolarizabilities, magnetizabilities, or optical rotations.[17,18,19,20,21,22,23,24,25]
Alternative local correlation approaches in the same spirit include the orbital-specific virtual idea of Yang et al.[39] and the local pair-natural-orbital (LPNO) approach recently reintroduced by Neese and co-workers.[40,41,42]
Summary
Quantum chemical methods such as coupled cluster theory[1,2,3,4] can provide robust and reliable simulations of both resonant and non-resonant interactions of molecules with electric and magnetic fields.[5]. This method was successfully applied to compute coupled cluster energies in various applications for periodic systems,[79,80,81,82,83,84,85,86,87,88,89,90] to closed-91–98 and open-shell molecular systems,[99,100] and recently to metals with a multireference wavefunction.[101] In the context of properties, Yang and Dolg computed static first- and second-order polarizabilities[102] and Friedrich et al computed dipole and quadrupole moments.[103] In this work we implemented the incremental CCSD polarizabilities within the PSI4 program package using the domain-specific basis set approach to reduce the computational effort. When attempting to achieve high accuracy coupled cluster calculations, it is necessary to include higher excitations in the calculations of the polarizabilities.[105]
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