Since the initial guess triples amplitudes, the local density fitting (LDF), and the TNO domains for each triplet ijk for our DLPNO-CCSDT algorithm are formed from our previously implemented DLPNO-CCSD(T) algorithm (described in more detail in reference 54), we deem it appropriate to give a very brief overview of the procedures and parameters used in our DLPNO-(T) algorithm. The DLPNO-CCSD(T) algorithm in our code combines features from the originally inspired DLPNO-CCSD(T) algorithm in ORCA as well as the PNO-LCCSD(T) algorithm in Molpro. First, we first compute a list of every possible triplet ijk, derived from combinations of pairs ij, jk, and ik, at least one of which is a strong pair. For efficiency in time and storage, we make use of restricted indexing i ≤ j ≤ k. The semicanonincal (T0) energy is computed for each possible triplet at a looser TNO tolerance (T CUT TNO PRE ). All triplets ijk with energy contributions lower than (T CUT TRIPLES PRE )