# Communication: four-component density matrix renormalization group.

@article{Knecht2014CommunicationFD, title={Communication: four-component density matrix renormalization group.}, author={Stefan Knecht and {\"O}rs Legeza and Markus Reiher}, journal={The Journal of chemical physics}, year={2014}, volume={140 4}, pages={ 041101 } }

We present the first implementation of the relativistic quantum chemical two- and four-component density matrix renormalization group algorithm that includes a variational description of scalar-relativistic effects and spin-orbit coupling. Numerical results based on the four-component Dirac-Coulomb Hamiltonian are presented for the standard reference molecule for correlated relativistic benchmarks: thallium hydride.

## 62 Citations

Self-consistent embedding of density-matrix renormalization group wavefunctions in a density functional environment.

- PhysicsThe Journal of chemical physics
- 2015

The frozen density embedding scheme is used with a freeze-and-thaw strategy for a self-consistent polarization of the orbital-optimized wavefunction and the environmental densities with respect to each other.

Relativistic kinetic-balance condition for explicitly correlated basis functions

- Physics
- 2015

This paper presents the derivation of a kinetic-balance condition for explicitly correlated basis functions employed in semi-classical relativistic calculations. Such a condition is important to…

Four-component full configuration interaction quantum Monte Carlo for relativistic correlated electron problems.

- PhysicsThe Journal of chemical physics
- 2020

The necessary modifications do not particularly adversely affect the convergence of the systematic (initiator) error to the exact correlation energy for FCIQMC calculations, allowing the computational effort to somewhat bypass the formal increases in Hilbert space dimension for these problems.

Massively parallel quantum chemical density matrix renormalization group method

- Physics, Computer ScienceJ. Comput. Chem.
- 2021

This work has developed the parallel scheme based on the in‐house MPI global memory library, which combines operator and symmetry sector parallelisms, and tested its performance on three different molecules, all typical candidates for QC‐DMRG calculations.

Spin orbit coupling for molecular ab initio density matrix renormalization group calculations: Application to g-tensors.

- Physics, ChemistryThe Journal of chemical physics
- 2015

Spin Orbit Coupling (SOC) is introduced to molecular ab initio density matrix renormalization group (DMRG) calculations and can be regarded as the molecular equivalent to atomic Russell-Saunders coupling.

Variational Relativistic Two-Component Complete-Active-Space Self-Consistent Field Method.

- PhysicsJournal of chemical theory and computation
- 2019

A two-component complete-active-space self-consistent field method that includes scalar relativistic effects and one-electron spin-orbit coupling during the self- Consistent wave function optimization procedure is presented.

A comparison between the one- and two-step spin-orbit coupling approaches based on the ab initio Density Matrix Renormalization Group

- Physics
- 2022

The eﬃcient and reliable treatment of both spin-orbit coupling (SOC) and electron correlation is essential for understanding f-element chemistry. We analyze two approaches to the problem, the…

Relativistic Kramers-Unrestricted Exact-Two-Component Density Matrix Renormalization Group.

- PhysicsThe journal of physical chemistry. A
- 2022

In this work we develop a variational relativistic density matrix renormalization group (DMRG) approach within the exact-two-component (X2C) framework (X2C-DMRG), using spinor orbitals optimized with…

Relativistic reduced density matrix functional theory.

- PhysicsSciPost Chemistry
- 2022

As a new approach to efficiently describe correlation effects in the relativistic quantum world we propose to consider reduced density matrix functional theory, where the key quantity is the…

A state interaction spin-orbit coupling density matrix renormalization group method.

- PhysicsThe Journal of chemical physics
- 2016

It is found that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.

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