We will present our recent progress in the multireference electronic structure methods based on the density matrix renormalization group (DMRG) theory and its partner dynamical correlation models. By virtue of the compact parameterization of the matrix product state (MPS) wavefunction used in the DMRG algorithm, the DMRG has promising capabilities for overcoming the exponential complexity in the CI treatment of the CAS reference. Near-exact solutions of CASSCF is now available with the DMRG-CASSCF for more than 100 active orbitals for quasi-one-dimensional molecules, and for 30-40 active orbitals for transition metal complexes where the one-dimensional structure of static correlation is absent. In chemistry, the remaining dynamical correlation is also crucial for obtaining meaningful results for molecular properties, such as bond lengths, reaction barrier, excitation energies, etc., therefore, we combined the DMRG-CASSCF with the multireference dynamical correlation theories developing an efficient methods for evaluating the higher-order reduced density matrices of the MPS wavefunctions, and those DMRG-based multireference correlation theories are now routinely used in the practical applications. In my talk, we will present our recent applications on π-conjugated molecules, and development of a quasi-diabatization scheme for MPS wavefunctions to obtain electronic-couplings associated with various phenomena in organic molecular aggregates.

Applications of density matrix renormalization group algorithm-based multireference correlation theories

251st National Meeting (2016)

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