Static Polarizabilities at the Basis Set Limit: A Benchmark of 124 Species.

Luigi Genovese,Stig Rune Jensen,Peter Wind,Marco D’Alessandro,Kathrin Helen Hopmann,Anders Brakestad,Luca Frediani

doi:10.1021/acs.jctc.0c00128

Abstract

Benchmarking molecular properties with Gaussian-type orbital (GTO) basis sets can be challenging, because one has to assume that the computed property is at the complete basis set (CBS) limit, without a robust measure of the error. Multiwavelet (MW) bases can be systematically improved with a controllable error, which eliminates the need for such assumptions. In this work, we have used MWs within Kohn–Sham density functional theory to compute static polarizabilities for a set of 92 closed-shell and 32 open-shell species. The results are compared to recent benchmark calculations employing the GTO-type aug-pc4 basis set. We observe discrepancies between GTO and MW results for several species, with open-shell systems showing the largest deviations. Based on linear response calculations, we show that these discrepancies originate from artifacts caused by the field strength and that several polarizabilies from a previous study were contaminated by higher order responses (hyperpolarizabilities). Based on our MW benchmark results, we can affirm that aug-pc4 is able to provide results close to the CBS limit, as long as finite difference effects can be controlled. However, we suggest that a better approach is to use MWs, which are able to yield precise finite difference polarizabilities even with small field strengths.

Highlights

Molecular electronic structure calculations are a widespread tool in chemistry, biology, and materials science
In order to assign errors to the right source, we have considered the following types of calculations: (1) Gaussian-type orbital (GTO)-finite differences (FD) calculations; (2) MW-FD calculations; (3) GTO-linear response (LR) calculations; (4) MW-LR calculatations
We have shown that GTO-FD polarizabilities presented by Hait and Head-Gordon[7] display quite large errors, considering the size of the aug-pc[4] basis set used

Summary

Introduction

Molecular electronic structure calculations are a widespread tool in chemistry, biology, and materials science. Such a diffusion across disciplines has been enabled by Kohn−Sham density functional theory (KS-DFT, hereafter just “DFT”)[1] which brought about calculations with accuracy comparable to coupled cluster with singles and doubles (CCSD) at the computational cost of a single-determinant method like Hartree−Fock (HF). A large part of the current development of theoretical methods is concerned with obtaining accurate energies, which are essential to interpret and predict chemical reactivity. Molecular properties constitute another important area of method development. Electric dipole polarizabilities are related to important processes in chemistry; for example, they hold a key role in our understanding of intra- and intermolecular interactions such as dispersion,[2,3] they are at the foundation of techniques such as Raman spectroscopy and Raman optical activity,[4] and they are employed in the development of accurate force fields for molecular simulations.[5,6] It is highly relevant to assess the accuracy of polarizability predictions within the density functional theory (DFT) framework

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Conclusion