Density-matrix renormalization group algorithm with multi-level active space

Ma, Yingjin; Wen, Jing; Ma, Hao

doi:10.1063/1.4926833

Cited by 21 publications

(18 citation statements)

References 116 publications

(118 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…cu(4) approximation, as has been done in conjunction with statespecific CASPT2, 459,460 NEVPT2, 455 and MRCI. 70 Extension in a different direction is exampled by developing of a multistate version of the DMRG-CASPT2 method by Yanai et al 461 DMRG-based methods have been used to calculate the lowest excited states of small systems LiF, 461,462 CH2, 463 HNCO, 464 C2, 465 N2, 466 Cr2, 466 ethylene, 457,467 H2O, 451,466 CsH, 468 CoH, 469 Fe2S2 , 435 NiCO, 470 a prototype of carbonyl metal complex, and moderate-sized molecules, e.g. uracil 471 and indole 466 to demonstrate efficiency of implemented algorithms.…”

Section: Dmrgmentioning

confidence: 99%

Multireference Approaches for Excited States of Molecules

et al. 2018

View full text Add to dashboard Cite

Understanding the properties of electronically excited states is a challenging task that becomes increasingly important for numerous applications in chemistry, molecular physics, molecular biology, and materials science. A substantial impact is exerted by the fascinating progress in time-resolved spectroscopy, which leads to a strongly growing demand for theoretical methods to describe the characteristic features of excited states accurately. Whereas for electronic ground state problems of stable molecules the quantum chemical methodology is now so well developed that informed nonexperts can use it efficiently, the situation is entirely different concerning the investigation of excited states. This review is devoted to a specific class of approaches, usually denoted as multireference (MR) methods, the generality of which is needed for solving many spectroscopic or photodynamical problems. However, the understanding and proper application of these MR methods is often found to be difficult due to their complexity and their computational cost. The purpose of this review is to provide an overview of the most important facts about the different theoretical approaches available and to present by means of a collection of characteristic examples useful information, which can guide the reader in performing their own applications.

show abstract

Section: Dmrgmentioning

confidence: 99%

Multireference Approaches for Excited States of Molecules

et al. 2018

View full text Add to dashboard Cite

show abstract

“…61 Particle number restriction is sufficient to implement the uncontracted multi-reference dynamical correlation approaches in this work, but extensions to other symmetry sectors (e.g., and 2 symmetry) is possible, and can, for example be used to describe wavefunctions restricted by the seniority quantum number. 60 In passing, we note that this approach is very different from the "multilevel" DMRG, 62 where different maximal bond dimensions are used in the three subspaces, without any restrictions on the particle number blocks.…”

Section: Methodsmentioning

confidence: 99%

Matrix product states with large sites

Larsson,

Zhai,

Gunst

et al. 2021

Preprint

View full text Add to dashboard Cite

We explore various ways to group orbitals into clusters in a matrix product state (MPS). We explain how a generic cluster MPS can often lead to an increase in computational cost and instead propose a special cluster structure, involving only the first and last orbitals/sites, with a wider scope for computational advantage. This structure is a natural formalism to describe correlated multireference (MR) theories. We demonstrate the flexibility and usefulness of this approach by implementing various uncontracted MR configuration interaction, perturbation and linearized coupled cluster theories using an MPS with large cluster sites. Applications to the nitrogen dimer, the chromium dimer, and benzene, including up to triple excitations in the external space, demonstrate the utility of an MPS with up to two large sites. We use our results to analyze the quality of different multireference approximations.

show abstract

“…In this context, we would like to mention that a different-type of RG approach, namely the density-matrix-renormalization-group (DMRG) method pioneered by White [96] has been also very successful for describing strong correlation of ground electronic states. However, in DMRG the criterion for the iterative truncation procedure is based on the reduced density matrix rather than in energy [96][97][98][99][100][101][102][103][104][105][106][107][108][109][110].…”

Section: Introductionmentioning

confidence: 99%

Seniority based energy renormalization group (Ω-ERG) approach in quantum chemistry: Initial formulation and application to potential energy surfaces

Bytautas

Dukelsky

2018

Computational and Theoretical Chemistry

View full text Add to dashboard Cite

This investigation combines the concept of the seniority number  (defined as the total number of singly occupied orbitals in a determinant) with the energy renormalization group (ERG) approach to obtain the lowest-energy electronic states on molecular potential energy surfaces. The proposed -ERG method uses Slater determinants that are ordered according to seniority number  in ascending order. In the -ERG procedure, the active system consists of M (N-electron) states and K additional complement (N-electron) states (complement-system). Among the M states in the active system the lowest-energy m states represent target states of interest (target-states), thus m  M. The environment consists of Full Configuration Interaction (FCI) determinants that represent a reservoir from which the complement-states K are being selected. The goal of the -ERG procedure is to obtain lowest-energy target states m of FCI quality in an iterative way at a reduced computational cost. In general, the convergence rate of -ERG energies towards FCI values depends on m and M, thus, the notation -ERG(m,M) is used. It is found that the -ERG(m,M) method can be very effective for calculating lowestenergy m (ground and excited) target states when a sufficiently large number of sweeps is used. We find that the fastest convergence is observed when M > m. The performance of the -ERG(m,M) procedure in describing strongly correlated molecular systems has been illustrated by examining bond-breaking processes in N2, H8, H2O and C2. The present, proof-of-principle study yields encouraging results for calculating multiple electronic states on potential energy surfaces with near Full CI quality.

show abstract

Density-matrix renormalization group algorithm with multi-level active space

Cited by 21 publications

References 116 publications

Multireference Approaches for Excited States of Molecules

Multireference Approaches for Excited States of Molecules

Matrix product states with large sites

Seniority based energy renormalization group (Ω-ERG) approach in quantum chemistry: Initial formulation and application to potential energy surfaces

Contact Info

Product

Resources

About