  We present an efficient implementation of the Density Matrix Renormalization
Group (DMRG) algorithm that includes an optimal ordering of the proton and
neutron orbitals and an efficient expansion of the active space utilizing
various concepts of quantum information theory. We first show how this new DMRG
methodology could solve a previous $400$ KeV discrepancy in the ground state
energy of $^{56}$Ni. We then report the first DMRG results in the $pf+g9/2$
shell model space for the ground $0^+$ and first $2^+$ states of $^{64}$Ge
which are benchmarked with reference data obtained from Monte Carlo shell
model. The corresponding correlation structure among the proton and neutron
orbitals is determined in terms of the two-orbital mutual information. Based on
such correlation graphs we propose several further algorithmic improvement
possibilities that can be utilized in a new generation of tensor network based
algorithms.
