I am doing some research and trying to make sure the numbers I am reporting are accurate.
I found that the paper by Sylvetsky et. al. says:
We were, however, able to complete a CCSDT(Q)/cc-pVTZ calculation on benzene, which entailed 2.2 trillion (Q) contributions and 3.1 billion iterative CCSDT amplitudes
But there is no indication that this was the largest number of amplitudes (3.1 billion), or largest number of perturbative contributions (2.2 trillion). Furthermore, the paper was done in 2016 so surely larger might have been possible since then.
Does anyone know what the largest couples cluster calculation done as of March 2019 was? By "largest" I mean containing the largest number of cluster amplitudes (of any excitation level).