The Density Matrix Renormalization Group for Strong Correlation in Ground and Excited States

Freitag, Leon; Reiher, Markus

doi:10.1002/9781119417774.ch7

Cited by 26 publications

(25 citation statements)

References 257 publications

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“…The active space limit can be pushed further up to the order of 100 orbitals in DMRG, 85 which uses tensor decomposition methods to approximate the CASSCF wave function. While for typical DMRG calculations, active space sizes of ∼50 orbitals are manageable, 86 when applying a subsequent second-order perturbational treatment to the DMRG wave function as in CASPT2 or NEVPT2 approaches to obtain more accurate electronic energies, the active space size that can be handled computationally decreases again to ∼30 orbitals 87 for a single-point energy calculation. Figure 2 c shows an example of a so-called entanglement diagram that can be obtained from a DMRG calculation to estimate the importance of different orbitals in an active space.…”

Section: Electronic Structure Methods For Dynamics Of Transition Metal Complexesmentioning

confidence: 99%

The Quest to Simulate Excited-State Dynamics of Transition Metal Complexes

Zobel

González

2021

JACS Au

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This Perspective describes current computational efforts in the field of simulating photodynamics of transition metal complexes. We present the typical workflows and feature the strengths and limitations of the different contemporary approaches. From electronic structure methods suitable to describe transition metal complexes to approaches able to simulate their nuclear dynamics under the effect of light, we give particular attention to build a bridge between theory and experiment by critically discussing the different models commonly adopted in the interpretation of spectroscopic experiments and the simulation of particular observables. Thereby, we review all the studies of excited-state dynamics on transition metal complexes, both in gas phase and in solution from reduced to full dimensionality.

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Section: Electronic Structure Methods For Dynamics Of Transition Metal Complexesmentioning

confidence: 99%

The Quest to Simulate Excited-State Dynamics of Transition Metal Complexes

Zobel

González

2021

JACS Au

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“…This way, the number of parameters entering the wave function ansatz definition is reduced from exponential, as it is in full CI, to polynomial. The optimization of MPS wave functions is most commonly carried out with the DMRG approach, for the explanation of which we refer the reader to the comprehensive reviews of Schollwöck , and ref .…”

Section: Theorymentioning

confidence: 99%

“…These limits can be reached very quickly, especially in polynuclear transition-metal complexes. One approach to overcome the exponential scaling of CASSCF is the density matrix renormalization group (DMRG) , for quantum chemistry, − which, combined with self-consistent field orbital optimization (DMRG-SCF), , is able to variationally approximate CASSCF wave functions to arbitrary accuracy at a polynomial instead of exponential scaling of the computational cost.…”

Section: Introductionmentioning

confidence: 99%

Simplified State Interaction for Matrix Product State Wave Functions

Freitag

Baiardi

Knecht

et al. 2021

J. Chem. Theory Comput.

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We present an approximation to the state-interaction approach for matrix product state (MPS) wave functions (MPSSI) in a nonorthogonal molecular orbital basis, first presented by Knecht et al. [ J. Chem. Theory Comput., 2016 , 28, 5881], that allows for a significant reduction of the computational cost without significantly compromising its accuracy. The approximation is well-suited if the molecular orbital basis is close to orthogonality, and its reliability may be estimated a priori with a single numerical parameter. For an example of a platinum azide complex, our approximation offers up to 63-fold reduction in computational time compared to the original method for wave function overlaps and spin–orbit couplings, while still maintaining numerical accuracy.

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“…Density matrix renormalization group (DMRG)[ 63 , 64 ] for quantum chemistry[ 65 , 66 , 67 , 68 , 69 ] provides a remedy to both the computational scaling and the CASSCF active space selection. It allows approximating a CASSCF calculation to an arbitrary accuracy with polynomial scaling with the active space size.…”

Section: Introductionmentioning

confidence: 99%

A Density Matrix Renormalization Group Study of the Low‐Lying Excited States of a Molybdenum Carbonyl‐Nitrosyl Complex

et al. 2021

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A density matrix renormalization group‐self consistent field (DMRG‐SCF) study has been carried out to calculate the low‐lying excited states of CpMo(CO)2NO, a molybdenum complex containing NO and CO ligands. In order to automatically select an appropriate active space, a novel procedure employing the maximum single‐orbital entropy for several states has been introduced and shown to be efficient and easy‐to‐implement when several electronic states are simultaneously considered. The analysis of the resulting natural transition orbitals and charge‐transfer numbers shows that the lowest five excited electronic states are excitation into metal‐NO antibonding orbitals, which offer the possibility for nitric oxide (NO) photorelease after excitation with visible light. Higher excited states are metal‐centered excitations with contributions of metal‐CO antibonding orbitals, which may serve as a gateway for carbon monoxide (CO) delivery. Time‐dependent density functional theory calculations done for comparison, show that the state characters agree remarkably well with those from DMRG‐SCF, while excitation energies are 0.4–1.0 eV red‐shifted with respect to the DMRG‐SCF ones.

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The Density Matrix Renormalization Group for Strong Correlation in Ground and Excited States

Cited by 26 publications

References 257 publications

The Quest to Simulate Excited-State Dynamics of Transition Metal Complexes

The Quest to Simulate Excited-State Dynamics of Transition Metal Complexes

Simplified State Interaction for Matrix Product State Wave Functions

A Density Matrix Renormalization Group Study of the Low‐Lying Excited States of a Molybdenum Carbonyl‐Nitrosyl Complex

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