In the first part of the talk, I will review basic concepts of quantum chemical density matrix renormalization group (QC-DMRG), the method of choice for calculations of strongly correlated molecular systems, which is especially suitable for treatment of one-dimensional and quasi one-dimensional problems. I will also present our recent developments on local orbital optimization matching the two-site DMRG scheme  and introduce MOLMPS, the massively parallel QC-DMRG implementation which is currently under development .
In the second part, I will introduce the recently developed method for accurate “post-DMRG” treatment of dynamic correlation based on the tailored coupled cluster (CC) theory  in which QC-DMRG is responsible for the proper description of non-dynamic correlation, whereas dynamic correlation is incorporated by CC .
 Ch. Krumnow and L. Veis, et al., Phys. Rev. Lett 117 (2016) 21040.
 L. Veis and J. Brabec, et al., in preparation.
 T. Kinoshita and O. Hino, et al., J. Chem. Phys. 123 (2005) 074106.
 L. Veis and A. Antalik, et al., J. Phys. Chem. Lett. 7 (2016) 4072.