CASSCF with Extremely Large Active Spaces Using the Adaptive Sampling Configuration Interaction Method

Levine, Daniel S.; Hait, Diptarka; Tubman, Norm M.; Lehtola, Susi; Whaley, K. Birgitta; Head‐Gordon, Martin

doi:10.1021/acs.jctc.9b01255

Cited by 128 publications

(232 citation statements)

References 94 publications

Supporting

Mentioning

219

Contrasting

Order By: Relevance

“…Here, we will only briefly compare the methods on the basis of their common traits and differences. The adaptive sampling CI [56][57][58][59][60] (ASCI), semistochastic heat-bath CI can use the semistochastic cluster-analysis-driven FCIQMC (CAD-FCIQMC) approach, 94,95 in which, in the spirit of the externally corrected CC methods, The main results of our study are summarized in Figure 1 (with the underlying numerical data tabulated in the SI). No error bars are provided given that these are derived differently in the various methods.…”

Section: Introductionmentioning

confidence: 99%

The Ground State Electronic Energy of Benzene

Eriksen

Anderson

Deustua

et al. 2020

J. Phys. Chem. Lett.

Self Cite

134

158

View full text Add to dashboard Cite

We report on the findings of a blind challenge devoted to determining the frozencore, full configuration interaction (FCI) ground state energy of the benzene molecule in a standard correlation-consistent basis set of double-ζ quality. As a broad international endeavour, our suite of wave function-based correlation methods collectively represents a diverse view of the high-accuracy repertoire offered by modern electronic structure theory. In our assessment, the evaluated high-level methods are all found to qualitatively agree on a final correlation energy, with most methods yielding an estimate of the FCI value around −863 mE H. However, we find the root-mean-square deviation of the energies from the studied methods to be considerable (1.3 mE H), which in light of the acclaimed performance of each of the methods for smaller molecular systems clearly displays the challenges faced in extending reliable, near-exact correlation methods to larger systems. While the discrepancies exposed by our study thus emphasize the fact that the current state-of-the-art approaches leave room for improvement, we still expect the present assessment to provide a valuable community resource for benchmark and calibration purposes going forward.

show abstract

Section: Introductionmentioning

confidence: 99%

The Ground State Electronic Energy of Benzene

Eriksen

Anderson

Deustua

et al. 2020

J. Phys. Chem. Lett.

Self Cite

134

158

View full text Add to dashboard Cite

show abstract

“…We note that all electrons are correlated in ph-AFQMC and κ-UOOMP2 calculations. action SCF (HCISCF) 46 , DMRG with pair DFT (DMRG-PDFT) 68 , and adaptively sampled CI SCF (ASCISCF) 47 . All of these methods require a specification of active space which can be as small as (8e, 11o) and as large as (44e, 44o).…”

Section: Essential Time-reversal Symmetry Breakingmentioning

confidence: 99%

“…This is where approximate Brückner orbitals provide nearly optimal single-reference trial wavefunctions for ph-AFQMC. We will also study a model iron porphyrin complex which has been a topic of controversy between two selected configuration interaction methods 46,47 . UHF exhibits artificial symmetry breaking, which could be removed by κ-OOMP2.…”

mentioning

confidence: 99%

Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C₃₆ Fullerene and an Iron Porphyrin Model Complex

Malone

Morales

2020

J. Chem. Theory Comput.

View full text Add to dashboard Cite

We present three distinct examples where phaseless auxiliary-field Quantum Monte Carlo (ph-AFQMC) can be reliably performed with a single-determinant trial wavefunction with essential symmetry breaking. We first utilized essential time-reversal symmetry breaking with ph-AFQMC to compute the triplet-singlet energy gap in the TS12 set. We found statistically better performance of ph-AFQMC with complexrestricted orbitals than with spin-unrestricted orbitals. We then showed the utilization of essential spin symmetry breaking when computing the single-triplet gap of a known biradicaloid, C 36 . ph-AFQMC with spin-unrestricted Hartree-Fock (ph-AFQMC+UHF) fails catastrophically even with spin-projection and predicts no biradicaloid character. With approximate Brückner orbitals obtained from regularized orbital-optimized second-order Møller-Plesset perturbation theory (κ-OOMP2), ph-1 arXiv:2001.05109v1 [physics.chem-ph] 15 Jan 2020 AFQMC quantitatively captures strong biradicaloid character of C 36 . Lastly, we applied ph-AFQMC to the computation of the quintet-triplet gap in a model iron porphyrin complex where brute-force methods with a small active space fail to capture the triplet ground state. We show unambiguously that neither triplet nor quintet is strongly correlated using UHF, κ-OOMP2, and coupled-cluster with singles and doubles (CCSD) performed on UHF and κ-OOMP2 orbitals. There is no essential symmetry breaking in this problem. By virtue of this, we were able to perform UHF+ph-AFQMC reliably with a cc-pVTZ basis set and predicted a triplet ground state for this model geometry. The largest ph-AFQMC in this work correlated 186 electrons in 956 orbitals.Our work highlights the utility, scalability, and accuracy of ph-AFQMC with a single determinant trial wavefunction with essential symmetry breaking for systems mainly dominated by dynamical correlation with little static correlation. LLNL-JRNL-801427-DRAFT

show abstract

“…22,39 The energy of the SCI wave function can be further lowered via rotation to an approximate natural orbital basis 3,23,39 or orbital optimization within the active space. 40,41 The remaining correlation energy could be estimated via other approaches like second order perturbation theory (PT2). 23,42 SCI+PT2 absolute energies in fact often readily converge to the chemical accuracy limit of 4 kJ/mol for even strongly correlated transition metal systems, 23,24 making them a useful option for transition metal quantum chemistry.…”

Section: P R O O Fmentioning

confidence: 99%

What Levels of Coupled Cluster Theory Are Appropriate for Transition Metal Systems? A Study Using Near-Exact Quantum Chemical Values for 3d Transition Metal Binary Compounds

Hait

Tubman

Levine

et al. 2019

J. Chem. Theory Comput.

Self Cite

View full text Add to dashboard Cite

Transition metal compounds are traditionally considered to be challenging for standard quantum chemistry approximations like coupled cluster (CC) theory, which are usually employed to validate lower level methods like density functional theory (DFT). To explore this issue, we present a database of bond dissociation energies (BDEs) for 74 spin states of 69 diatomic species containing a 3d transition metal atom and a main group element, in the moderately sized def2-SVP basis. The presented BDEs appear to have an (estimated) 3σ error less than 1 kJ/mol relative to the exact solutions to the nonrelativistic Born−Oppenheimer Hamiltonian. These benchmark values were used to assess the performance of a wide range of standard single reference CC models, as the results should be beneficial for understanding the limitations of these models for transition metal systems. We find that interactions between metals and monovalent ligands like hydride and fluoride are well described by CCSDT. Similarly, CCSDTQ appears to be adequate for bonds between metals and nominally divalent ligands like oxide and sulfide. However, interactions with polyvalent ligands like nitride and carbide are more challenging, with even CCSDTQ(P) Λ yielding errors on the scale of a few kJ/mol. We also find that many perturbative and iterative approximations to higher order terms either yield disappointing results or actually worsen the performance relative to the baseline low level CC method, indicating that complexity does not always guarantee accuracy.

show abstract

CASSCF with Extremely Large Active Spaces Using the Adaptive Sampling Configuration Interaction Method

Cited by 128 publications

References 94 publications

The Ground State Electronic Energy of Benzene

The Ground State Electronic Energy of Benzene

Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C₃₆ Fullerene and an Iron Porphyrin Model Complex

What Levels of Coupled Cluster Theory Are Appropriate for Transition Metal Systems? A Study Using Near-Exact Quantum Chemical Values for 3d Transition Metal Binary Compounds

Contact Info

Product

Resources

About

CASSCF with Extremely Large Active Spaces Using the Adaptive Sampling Configuration Interaction Method

Cited by 128 publications

References 94 publications

The Ground State Electronic Energy of Benzene

The Ground State Electronic Energy of Benzene

Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C36 Fullerene and an Iron Porphyrin Model Complex

What Levels of Coupled Cluster Theory Are Appropriate for Transition Metal Systems? A Study Using Near-Exact Quantum Chemical Values for 3d Transition Metal Binary Compounds

Contact Info

Product

Resources

About

Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C₃₆ Fullerene and an Iron Porphyrin Model Complex