The ab initio density matrix renormalization group (DMRG) method has been well-established and has become one of the most accurate numerical methods for the precise electronic structure solution of large active spaces. In the past few years, to capture the missing dynamic correlation, various post-DMRG approaches have been proposed through the combination of DMRG and multireference quantum chemical methods or density functional theory. With this in mind, this work provides a brief overview of ab initio DMRG principles and the new developments within post-DMRG methods. For clarity, post-DMRG methods are classified into two main categories depending on whether high-order n -electron reduced density matrices are used, and their merits and disadvantages are properly discussed. Finally, we conclude by discussing unsolved bottlenecks and giving development perspectives of post-DMRG approaches, which are expected to yield quantitative descriptions of complex electronic structures in large strongly correlated molecules and materials.The ab initio density matrix renormalization group (DMRG) method has been well-established and has become one of the most accurate numerical methods for the precise electronic structure solution of large active spaces. In the past few years, to capture the missing dynamic correlation, various post-DMRG approaches have been proposed through the combination of DMRG and multireference quantum chemical methods or density functional theory. With this in mind, this work provides a brief overview of ab initio DMRG principles and the new developments within post-DMRG methods. For clarity, post-DMRG methods are classified into two main categories depending on whether high-order n -electron reduced density matrices are used, and their merits and disadvantages are properly discussed. Finally, we conclude by discussing unsolved bottlenecks and giving development perspectives of post-DMRG approaches, which are expected to yield quantitative descriptions of complex electronic structures in large strongly correlated molecules and materials.

The Journal of Physical Chemistry LettersJan 20, 202244 citations

Ab Initio Density Matrix Renormalization Group Methodology And Computational Transition Metal Chemistry

Johannes Hachmann

This thesis is concerned with two topics from the ﬁeld of computational electronic structure theory. In the ﬁrst part we will describe our contributions to the ab initio density matrix renormalization group (DMRG) methodology in quantum chemistry, in particular our quadratically scaling local algorithm. We will present applications aimed towards new insights into the physics of conjugated π-electron systems as found, e.g., in organic electronic materials. The second part of this thesis covers our computational study of 3d-M(smif)2 complexes synthesized and characterized in the Wolczanski Group. These compounds exhibit unusual electronic structure phenomena which we address from a theoretical perspective.This thesis is concerned with two topics from the ﬁeld of computational electronic structure theory. In the ﬁrst part we will describe our contributions to the ab initio density matrix renormalization group (DMRG) methodology in quantum chemistry, in particular our quadratically scaling local algorithm. We will present applications aimed towards new insights into the physics of conjugated π-electron systems as found, e.g., in organic electronic materials. The second part of this thesis covers our computational study of 3d-M(smif)2 complexes synthesized and characterized in the Wolczanski Group. These compounds exhibit unusual electronic structure phenomena which we address from a theoretical perspective.

Apr 9, 20100 citations

Electronic Structure Calculations with LDA $+$ DMFT

Eva Pavarini

arXiv:1411.6906Mathematical physics studiesJan 1, 20148 citations

On the importance of orbital localization in QC‐DMRG calculations

Alexander O. Mitrushchenkov, G. Fano, Roberto Linguerri +1 more

Abstract We investigate the importance of orbital localization in the application of the Density Matrix Renormalization Group (DMRG) technique to ab initio studies of molecular electronic structure. Our previous implementation of DMRG has been generalized to allow for the use of localized nonorthogonal orbitals. Simple cycles of equidistant hydrogen atoms, which are good examples of one dimensional metal‐like lattices with fully delocalized electronic structures, have been taken as test models. In this study, the efficiency of the DMRG method and the importance of orbital localization for the generation of the DMRG building blocks are confirmed. However, it is found that the convergence of the procedure based on nonorthogonal orbitals is slower and requires more DMRG components than the standard orthogonal formulation. Symmetrically orthonormalized atomic orbitals are shown to be a good compromise solution: they satisfy the requirement of orbital localization for the generation of the DMRG blocks and improve the convergence, reducing the number of components of the DMRG expansion. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012Abstract We investigate the importance of orbital localization in the application of the Density Matrix Renormalization Group (DMRG) technique to ab initio studies of molecular electronic structure. Our previous implementation of DMRG has been generalized to allow for the use of localized nonorthogonal orbitals. Simple cycles of equidistant hydrogen atoms, which are good examples of one dimensional metal‐like lattices with fully delocalized electronic structures, have been taken as test models. In this study, the efficiency of the DMRG method and the importance of orbital localization for the generation of the DMRG building blocks are confirmed. However, it is found that the convergence of the procedure based on nonorthogonal orbitals is slower and requires more DMRG components than the standard orthogonal formulation. Symmetrically orthonormalized atomic orbitals are shown to be a good compromise solution: they satisfy the requirement of orbital localization for the generation of the DMRG blocks and improve the convergence, reducing the number of components of the DMRG expansion. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012

International Journal of Quantum ChemistryDec 29, 201126 citations

Impurity properties from DMRG: a thermodynamic approach.

Stefan Rommer, Sebastian Eggert

APSMar 1, 19980 citations