Toward DMRG-tailored coupled cluster method in the 4c-relativistic domain

Brandejs, Jan; Višňák, Jakub; Veis, Libor; Maté, Mihály; Legeza, Örs; Pittner, Jiřı́

doi:10.1063/1.5144974

Cited by 23 publications

(17 citation statements)

References 45 publications

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“…The underlying mathematical framework, however, is not restricted to models studied in condensed matter physics 65,66 or applications to molecular clusters 51,64,67 but among many others it can be also used to study nuclear shell models, [68][69][70][71] , particles in confined potential [72][73][74] or problems in the relativistic domain. [75][76][77] Therefore, mapping a physical problem to a proper model together with an optimal choice of basis could pave the road for DMRG applications in a broad range of disciplines which could surpass conventional methods.…”

Section: Introductionmentioning

confidence: 99%

DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride

Barcza

Ivády

Szilvási

et al. 2021

J. Chem. Theory Comput.

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In this paper, we analyze the numerical aspects of the inherently multi-reference density matrix renormalization group (DMRG) calculations on top of the periodic Kohn-Sham density functional theory (DFT) using the complete active space (CAS) approach. The potential of the framework is illustrated by studying hexagonal boron nitride (hBN) nano-flakes embedding a charged single boron vacancy point defect by revealing a vertical energy spectrum with prominent multi-reference character. We investigate the consistency of the DMRG energy spectrum from the perspective of sample size, basis size, and active space selection protocol. Results obtained from standard quantum chemical atom-centered basis calculations and plane-wave based counterparts show excellent agreement. Furthermore, we also discuss the spectrum of the periodic sheet which is in good agreement with extrapolated data of finite clusters. These results pave the way toward applying DMRG method in extended correlated solid state systems, such as point qubit in wide band gap semiconductors.

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Section: Introductionmentioning

confidence: 99%

DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride

Barcza

Ivády

Szilvási

et al. 2021

J. Chem. Theory Comput.

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“…However, this does mean that methods which excel in their application to statically correlation, such as DMRG and FCIQMC, are only likely to achieve good comparison to experiment upon expansion to a large basis set, which is unnecessarily costly for these methods. Recent developments have coupled active space 4c-DMRG calculations with large basis corrections, via multi-reference perturbation theory 13,14 , range-separated DFT 46 and tailored coupled cluster approaches [47][48][49] . While this has been performed for FCIQMC in a non-relativistic framework previously, this is a clear research direction to pursue 50,51 .…”

Section: A the Additional Cost Of 4c-fciqmcmentioning

confidence: 99%

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

Booth

2020

The Journal of Chemical Physics

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An adaptation of the full configuration interaction quantum Monte Carlo (FCIQMC) method is presented, for correlated electron problems containing heavy elements and the presence of significant relativistic effects. The modified algorithm allows for the sampling of the four-component spinors of the Dirac-Coulomb(-Breit) Hamiltonian within the relativistic no-pair approximation. The loss of spin symmetry and the general requirement for complex-valued Hamiltonian matrix elements are the most immediate considerations in expanding the scope of FCIQMC into the relativistic domain, and the alternatives for their efficient implementation are motivated and demonstrated. For the canonical correlated four-component chemical benchmark application of Thallium Hydride, we show that the necessary modifications do not particularly adversely affect the convergence of the systematic (initiator) error to the exact correlation energy for FCIQMC calculations, which is primarily dictated by the sparsity of the wave function, allowing the computational effort to somewhat bypass the formal increases in Hilbert space dimension for these problems. We apply the method to the larger problem of the spectroscopic constants of Tin Oxide, correlating 28 electrons in 122 Kramers-paired spinors, finding good agreement with experimental and prior theoretical relativistic studies.

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“…Recent studies report that local pair natural orbitals and domain-based local pair natural orbitals perform better than canonical RHF orbitals in DMRG-tCCSD. 20,[85][86][87] Here, we benchmark another type of orbitals of localized nature, namely pCCD-optimized orbitals as they have not yet been combined with coupled cluster theory tailored by DMRG wave functions.…”

Section: Introductionmentioning

confidence: 99%

Assessing the accuracy of tailored coupled cluster methods corrected by electronic wave functions of polynomial cost

Leszczyk¹,

Maté²,

Legeza³

et al. 2021

Preprint

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Tailored coupled cluster theory represents a computationally inexpensive way to describe static and dynamical electron correlation effects. In this work, we scrutinize the performance of various tailored coupled cluster methods externally corrected by electronic wave functions of polynomial cost. Specifically, we focus on frozen-pair coupled-cluster (fpCC) methods, which are externally corrected by pair-coupled cluster doubles (pCCD), and coupled cluster theory tailored by matrix product state wave functions optimized by the density matrix renormalization group (DMRG) algorithm. As test system, we selected a set of various small-and medium-sized molecules containing diatomics (N 2 , F 2 , C 2 , CN + , BN, BO + , and Cr 2 ) and molecules (ammonia, ethylene, cyclobutadiene, benzene) for which conventional single-reference coupled cluster singles and doubles (CCSD) is not able to produce accurate results for spectroscopic constants, potential energy surfaces, and barrier heights. Most importantly, DMRG-tailored and pCCD-tailored approaches yield similar errors in spectroscopic constants and potential energy surfaces compared to multireference and/or experimental reference data and generally outrank the conventional single-reference CCSD approach. Although fpCC methods provide a reliable description for the dissociation pathway of molecules featuring single and quadruple bonds, they fail in the description of triple or hextuple bond-breaking processes or avoided crossing regions.

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Toward DMRG-tailored coupled cluster method in the 4c-relativistic domain

Cited by 23 publications

References 45 publications

DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride

DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride

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

Assessing the accuracy of tailored coupled cluster methods corrected by electronic wave functions of polynomial cost

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