We have found that in common, from almost all the models of the SARS-CoV-2 3CLpro dimer, there are two polar contacts between GLU290 and ARG4 linking the two monomers. This article is to confirm this observation from optimization and molecular dynamics analyses of the open access molecular dynamics trajectory databases (zenodo.org/record/7401989) of the 3CLpro-monomer/dimer without ligand. All the hydrogen bonds linking the two monomers are also worth keeping our eyes open.