Reliability of CCSDT versus high-bond-dimension DMRG for stretched circumcoronene

Determine whether CCSDT or high-bond-dimension DMRG provides a more reliable estimate of the ground-state energy of circumcoronene with carbon–carbon bonds stretched by 10%.

Background

The paper studies circumcoronene with its C–C bonds stretched by 10% as a test of Selected Coupled Cluster (SCC) in a more strongly correlated regime. Because single-reference coupled-cluster methods may become unreliable under bond stretching and DMRG convergence depends on bond dimension, the authors report that the available CCSDT and high-bond-dimension DMRG calculations do not establish which method gives the more trustworthy ground-state energy for this system.