Post-density matrix renormalization group

Ma, Hao; Schollwöck, Ulrich; Shuai, Zhigang

doi:10.1016/b978-0-323-85694-2.00009-7

Cited by 2 publications

(2 citation statements)

References 116 publications

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“…The excitation could be categorized into three classes: internal [excitations inside internal (core and active) space], semi-internal (one excitation inside internal space and another from internal to external space), and external (excitations from internal to external space). Consequently, contracting different excitation classes results in different IC schemes. , For example, all three excitation classes are contracted in FIC-MRCI, while only the external excitation class is contracted in WK-MRCI. , The externally contracted multireference configuration interaction (EC-MRCI) groups the configurations with the same internal parts, while the contraction coefficients are generated by perturbation theory. Thus, the dimension of the Hamiltonian matrix is independent of external orbitals but dependent on reference configurations.…”

Section: Introductionmentioning

confidence: 99%

Spin-Adapted Externally Contracted Multireference Configuration Interaction Method Based on Selected Reference Configurations

Song,

Huang,

Liu

et al. 2024

J. Phys. Chem. A

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As one kind of approximation of the full configuration interaction solution, the selected configuration interaction (sCI) methods have been shown to be valuable for large active spaces. However, the inclusion of dynamic correlation beyond large active spaces is necessary for more quantitative results. Since the sCI wave function can provide a compact reference for multireference methods, previously, we proposed an externally contracted multireference configuration interaction method using the sCI reference reconstructed from the density matrix renormalization group wave function [J. Chem. Theory Comput. 2018, 14, 4747−4755]. The DMRG2sCI-EC-MRCI method is promising for dealing with more than 30 active orbitals and large basis sets. However, it suffers from two drawbacks: spin contamination and low efficiency when using Slater determinant bases. To solve these problems, in this work, we adopt configuration state function bases and introduce a new algorithm based on the hybrid of tree structure for convenient configuration space management and the graphical unitary group approach for efficient matrix element calculation. The test calculation of naphthalene shows that the spin-adapted version could achieve a speed-up of 6.0 compared with the previous version based on the Slater determinant. Examples of dinuclear copper(II) compound as well as Ln(III) and An(III) complexes show that the sCI-EC-MRCI can give quantitatively accurate results by including dynamic correlation over sCI for systems with large active spaces and basis sets.

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Section: Introductionmentioning

confidence: 99%

Spin-Adapted Externally Contracted Multireference Configuration Interaction Method Based on Selected Reference Configurations

Song,

Huang,

Liu

et al. 2024

J. Phys. Chem. A

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“…This necessitates the use of multireference (MR) methods, which address both configurations (CFGs) within CAS and excited CFGs generated from CAS. Recently, a variety of innovative MR methodologies specifically designed to integrate seamlessly with large-active-space FCI solvers have emerged, addressing the challenges posed by complex molecular systems. − These methods include the integration of DMRG with MR configuration interaction (MRCI)/perturbation theory (MRPT), − sCI+PT2, − stochastic MRCI/PT, − DMRG-canonical transformation (CT), , DMRG-based externally corrected coupled cluster (ec-CC), DMRG-tailored CC (TCC), − DFT integrated with DMRG, − and DMRG-adiabatic connection (AC). , Among these innovations, MRCI stands out for preserving CI methods’ key feature: energy variation. To uphold this trait while simultaneously managing the extensive number of excited CFGs in MRCI, the concept of the contracted approximation was introduced.…”

Section: Introductionmentioning

confidence: 99%

Renormalized-Residue-Based Multireference Configuration Interaction Method for Strongly Correlated Systems

Cheng,

2024

J. Chem. Theory Comput.

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The implementation of multireference configuration interaction (MRCI) methods in quantum systems with large active spaces is hindered by the expansion of configuration bases or the intricate handling of reduced density matrices (RDMs). In this work, we present a spin-adapted renormalized-residue-based MRCI (RR-MRCI) approach that leverages renormalized residues to effectively capture the entanglement between active and inactive orbitals. This approach is reinforced by a novel efficient algorithm, which also facilitates an efficient deployment of spin-adapted matrix product state MRCI (MPS-MRCI). The RR-MRCI framework possesses several advantages: (1) It considers the orbital entanglement and utilizes highly compressed MPS structure, improving computational accuracy and efficiency compared with internally contracted (ic) MRCI. (2) Utilizing small-sized buffer environments of a few external orbitals as probes based on quantum information theory, it enhances computational efficiency over MPS-MRCI and offers potential application to large molecular systems. (3) The RR framework can be implemented in conjunction with ic-MRCI, eliminating the need for highrank RDMs, by using distinct renormalized residues. We evaluated this method across nine diverse molecular systems, including Cu 2 O 2 2+ with an active space of (24e,24o) and two complexes of lanthanide and actinide with active space (38e,36o), demonstrating the method's versatility and efficacy.

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Post-density matrix renormalization group

Cited by 2 publications

References 116 publications

Spin-Adapted Externally Contracted Multireference Configuration Interaction Method Based on Selected Reference Configurations

Spin-Adapted Externally Contracted Multireference Configuration Interaction Method Based on Selected Reference Configurations

Renormalized-Residue-Based Multireference Configuration Interaction Method for Strongly Correlated Systems

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