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

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.