Excited States of Methylene, Polyenes, and Ozone from Heat-Bath Configuration Interaction

Chien, Alan D.; Holmes, Adam; Otten, Matthew; Umrigar, C. J.; Sharma, Sandeep; Zimmerman, Paul M.

doi:10.1021/acs.jpca.8b01554

Cited by 123 publications

(204 citation statements)

References 114 publications

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“…Let us now turn our attention to the excited states of three pseudo-linear π-conjugated systems that have been the subject to several investigations in the past, namely, acrolein, 27,[119][120][121][129][130][131][132][133] butadiene, 23,26,27,72,120,130,[134][135][136][137][138][139][140][141][142][143][144][145] and glyoxal. 27,116,120,130,132,[146][147][148][149] Among these works, it is worth highlighting the detailed theoretical investigation of Saha, Ehara, and Nakatsuji, who reported a huge number of ES for these three systems using a coherent theoretical protocol based on the symmetry-adapted-cluster configuration interaction (SAC-CI) method.…”

Section: Acrolein Butadiene and Glyoxalmentioning

confidence: 99%

“…These two values are slightly lower than the semi-stochastic heath-bath CI data obtained by Chien et al with a double-ζ basis and a slightly different geometry: 6.45 and 6.58 eV for B u and A g , respectively. 143 For these two thoroughly studied ES, one can of course find many other estimates, e.g., at the SAC-CI, 130 CC3, 26,27 CASPT2, 26 and NEVPT2 142 levels. Globally, for butadiene, we find an excellent coherence between the CC3, CCSDT, and CCSDTQ estimates, that all fall in a ±0.02 eV window.…”

Section: Acrolein Butadiene and Glyoxalmentioning

confidence: 99%

See 1 more Smart Citation

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

Loos

Lipparini²,

Boggio‐Pasqua³

et al. 2019

Preprint

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Following our previous work focussing on compounds containing up to 3 non-hydrogen atoms [J. Chem. Theory Comput. 14 (2018) [4360][4361][4362][4363][4364][4365][4366][4367][4368][4369][4370][4371][4372][4373][4374][4375][4376][4377][4378][4379], we present here highly-accurate vertical transition energies obtained for 27 molecules encompassing 4, 5, and 6 non-hydrogen atoms: equation-of-motion coupled cluster theory up to the highest technically possible excitation order for these systems (CC3, EOM-CCSDT, and EOM-CCSDTQ), selected configuration interaction 1 arXiv:1912.04173v2 [physics.chem-ph] 31 Jan 2020 (SCI) calculations (with tens of millions of determinants in the reference space), as well as the multiconfigurational n-electron valence state perturbation theory (NEVPT2) method. All these approaches are applied in combination with diffuse-containing atomic basis sets. For all transitions, we report at least CC3/aug-cc-pVQZ vertical excitation energies as well as CC3/aug-cc-pVTZ oscillator strengths for each dipole-allowed transition. We show that CC3 almost systematically delivers transition energies in agreement with higher-level methods with a typical deviation of ±0.04 eV, except for transitions with a dominant double excitation character where the error is much larger. The present contribution gathers a large, diverse and accurate set of more than 200 highly-accurate transition energies for states of various natures (valence, Rydberg, singlet, triplet, n → π , π → π , . . . ). We use this series of theoretical best estimates to benchmark a series of popular methods for excited state calculations: CIS(D), ADC(2), CC2, STEOM-CCSD, EOM-CCSD, CCSDR(3), CCSDT-3, CC3, as well as NEVPT2. The results of these benchmarks are compared to the available literature data.Although these conclusions agree well with earlier studies, 69-71 they obviously only hold for single excitations, i.e., transitions with %T 1 in the 80-100% range. Therefore, we also recently proposed a set of 20 TBE for transitions exhibiting a significant double-excitation character (i.e., with %T 1 typically below 80%). 72 Unsurprisingly, our results clearly evidenced that the error in CC methods is intimately related to the %T 1 value. For example, for the ES with a significant yet not dominant double excitation character [such as the infamous A g ES of butadiene (%T 1 = 75%)] CC methods including triples deliver rather accurate estimates (MAE of 0.11 eV with CC3 and 0.06 eV with CCSDT), surprisingly outperforming second-order multi-reference schemes such as CASPT2 or the generally robust n-electron valence state perturbation theory (NEVPT2). In contrast, for ES with a dominant double excitation character, e.g., the low-lying (n, n) → (π , π ) excitation in nitrosomethane (%T 1 = 2%), single-reference methods (not including quadruples) have been found to be unsuitable with MAEs of 0.86 and 0.42 eV for CC3 and CCSDT, respectively. In this case, multiconfigurational methods are in practice required to obtain accurate results. 72 A clear limit of ...

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Section: Acrolein Butadiene and Glyoxalmentioning

confidence: 99%

Section: Acrolein Butadiene and Glyoxalmentioning

confidence: 99%

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

Loos

Lipparini²,

Boggio‐Pasqua³

et al. 2019

Preprint

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“…Recently Blunt 12 has proposed a perturbative correction to estimate the initiator error with respect to a variational estimate of the i-FCIQMC energy obtained from the reduced density matrices. This method is in the spirit of the Epstein-Nesbet PT2 correction 13,14 of the selected CI methods such as CIPSI 15 , Heatbath CI 16 , and other adaptive methods [17][18][19][20] . These methods can be used to extrapolate to the E P T 2 → 0 limit, thereby producing estimates of the FCI energy.…”

Section: Introductionmentioning

confidence: 99%

Unbiasing the initiator approximation in full configuration interaction quantum Monte Carlo

Ghanem

Lozovoi

Alavi

2019

The Journal of Chemical Physics

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We identify and rectify a crucial source of bias in the initiator FCIQMC algorithm. Noninitiator determinants (i.e. determinants whose population is below the initiator threshold) are subject to a systematic undersampling bias, which in large systems leads to a bias in the energy when an insufficient number of walkers is used. We show that the acceptance probability (p acc ), that a non-initiator determinant has its spawns accepted, can be used to unbias the initiator bias, in a simple and accurate manner, by reducing the applied shift to the non-initiator proportionately to p acc . This modification preserves the property that in the large walker limit, when p acc → 1, the unbiasing procedure disappears, and the initiator approximation becomes exact. We demonstrate that this algorithm shows rapid convergence to the FCI limit with respect to walker number, and furthermore largely removes the dependence of the algorithm on the initiator threshold, enabling highly accurate results to be obtained even with large values of the threshold. This is exemplified in the case of butadiene/ANO-L-pVDZ and benzene/cc-pVDZ, correlating 22 and 30 electrons in 82 and 108 orbitals respectively. In butadiene 5 × 10 7 and in benzene 10 8 walkers suffice to obtain an energy to within a milli-Hartree of the CCSDT(Q) result, in Hilbert spaces of 10 26 and 10 35 respectively. Essentially converged results require ∼ 10 8 walkers for butadiene and ∼ 10 9 walkers for benzene, and lie slightly lower than CCSDT(Q). Owing to large-scale parallelisability, these calculations can be executed in a matter of hours on a few hundred processors. The present method largely solves the initiator-bias problems that the initiator method suffered from when applied to medium-sized molecules.

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“…1 and reported in Table I alongside reference values from the literature obtained with various deterministic and stochastic approaches. 63,66,70,72 Total energies for each state can be found in the supporting information. e exFCI/CBS values are still o by a few tenths of a kcal/mol compared to the DMC results of Zimmerman et al 70 which are extremely close from the experimentallyderived adiabatic energies.…”

Section: A Methylenementioning

confidence: 99%

Chemically Accurate Excitation Energies With Small Basis Sets

Giner¹,

Scemama²,

Toulouse³

et al. 2019

Preprint

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By combining extrapolated selected con guration interaction (sCI) energies obtained with the CIPSI (Con guration Interaction using a Perturbative Selection made Iteratively) algorithm with the recently proposed shortrange density-functional correction for basis-set incompleteness [Giner et al., J. Chem. Phys. 2018, 149, 194301], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-ζ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer and ethylene). e present study clearly evidences that special care has to be taken with very di use excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.

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Excited States of Methylene, Polyenes, and Ozone from Heat-Bath Configuration Interaction

Cited by 123 publications

References 114 publications

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

Unbiasing the initiator approximation in full configuration interaction quantum Monte Carlo

Chemically Accurate Excitation Energies With Small Basis Sets

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