Additional term in making matrix elements of similarily transformed hamiltonian

[DavidGoing]

In the code of making matrix elements of similarily transformed hamiltonian(coupled cluster/RHF/helper_cchbar). The notes tell that these term only differ by one sign. However, additional term appears in build_Hovvo, making the hamiltonian no longer antisymmetric. I am wondering what happened and why this term is needed.

[lothian]

In a spin-adapted RHF formalism, these two terms are distinct. Antisymmetry of the integrals and HBAR matrix elements only applies in a spin-orbital formulation.