Bootstrap Embedding\nfor Molecules in Extended Basis\nSets

Quantum embedding methods are powerful tools to exploit\nthe locality\nof electron correlation, but thus far many wave function-in-wave function\nmethods have focused on small (e.g., minimal) basis sets. One major\nchallenge for extended basis sets lies in defining consistent atom-\nor fragment-localized orbitals in spite of the larger spatial extent\nof the underlying atomic orbitals. In this work, we modify a particular\nform of quantum embedding, bootstrap embedding (BE), to the case of\nextended basis sets. We find that using intrinsic atomic orbital (IAO)\nlocalization schemes alongside BE converges to ∼99.7% of the\nCCSD correlation energy in 3-21G, 6-311G, and cc-pVDZ basis sets for\nreasonably sized fragments. These results mark an important first\nstep in extending the success of embedding methods to properly studying\ndynamic correlation.