Bootstrap Embedding for Molecules in Extended Basis Sets

Quantum embedding methods are powerful tools to exploit
the locality
of electron correlation, but thus far many wave function-in-wave function
methods have focused on small (e.g., minimal) basis sets. One major
challenge for extended basis sets lies in defining consistent atom-
or fragment-localized orbitals in spite of the larger spatial extent
of the underlying atomic orbitals. In this work, we modify a particular
form of quantum embedding, bootstrap embedding (BE), to the case of
extended basis sets. We find that using intrinsic atomic orbital (IAO)
localization schemes alongside BE converges to ∼99.7% of the
CCSD correlation energy in 3-21G, 6-311G, and cc-pVDZ basis sets for
reasonably sized fragments. These results mark an important first
step in extending the success of embedding methods to properly studying
dynamic correlation.