Shape resonance of sulphur dioxide anion excited states using the CAP-CIP-FSMRCCSD method

Basumallick, Suhita; Bhattacharya, Sumantra; Jana, Irina; Vaval, Nayana; Pal, Sourav

doi:10.1080/00268976.2020.1726521

Cited by 7 publications

(10 citation statements)

References 57 publications

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“…Jana and Nandi’s experiment reported the second state to be a mixed state, which is difficult to calculate theoretically. Hence, taking a higher 2 A 1 state, the resonance and width were reported as 6.51 and 0.97 eV, respectively …”

Section: Application Of Cap-fsccmentioning

confidence: 99%

“…Subtracting the E SRCC (g 1 ) value from E SO 2 − (g 2 ), we obtain the complex adiabatic EA for the state at g 2 geometry using the augcc-pVTZ basis set and a box size of 12, 6, and 6 au in the x, y, and z directions, respectively, and report the resonance energies of 4.45 eV and a width of 0.38 eV for the first 2 A 1 state. 168 The width is not known experimentally. The resonance position agrees with Krishnakumar's results better.…”

Section: Application Of Cap-fsccmentioning

confidence: 99%

“…Hence, taking a higher 2 A 1 state, the resonance and width were reported as 6.51 and 0.97 eV, respectively. 168…”

Section: Application Of Cap-fsccmentioning

confidence: 99%

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Negative Ion Resonance States: The Fock-Space Coupled-Cluster Way

et al. 2020

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The negative ion resonance states, which are electronmolecule metastable compound states, play the most important role in free-electron controlled molecular reactions and low-energy free-electroninduced DNA damage. Their electronic structure is often only poorly described but crucial to an understanding of their reaction dynamics. One of the most important challenges to current electronic structure theory is the computation of negative ion resonance states. As a major step forward, coupled-cluster theories, which are well-known for their ability to produce the best approximate bound state electronic eigen solutions, are upgraded to offer the most accurate and effective approximations for negative ion resonance states. The existing Fock-space coupled-cluster (FSCC) and the equation-ofmotion coupled-cluster (EOM-CC) approaches that compute bound states are redesigned for the direct and simultaneous determination of both the kinetic energy of the free electron at which the electron-molecule compound states are resonantly formed and the corresponding autodetachment decay rate of the electron from the metastable compound state. This Feature Article reviews the computation of negative ion resonances using the FSCC approach and, in passing, provides the highlights of the equivalent EOM-CC approach.

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Section: Application Of Cap-fsccmentioning

confidence: 99%

Section: Application Of Cap-fsccmentioning

confidence: 99%

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Negative Ion Resonance States: The Fock-Space Coupled-Cluster Way

et al. 2020

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“…The approximation is motivated by a perturbative analysis [47]. A similar analysis exists for the ionization potential [52]. Furthermore, we start from the SRCC similarity-transformed Hamiltonian, and this (0,0) sector has been kept truncated at the singles and doubles labels.…”

Section: Approximate Triplets: Perturbative Analysismentioning

confidence: 99%

“…Their approach is not only applicable for complete model spaces, but it is also applicable for incomplete model spaces. Moreover, the implementations of the complex absorbing potential (CAP) in the FSMRCC framework for resonant states, have also been achieved by Pal and co-workers [46,[50][51][52].…”

Section: Introductionmentioning

confidence: 99%

Three-Body Excitations in Fock-Space Coupled-Cluster: Fourth Order Perturbation Correction to Electron Affinity and Its Relation to Bondonic Formalism

Basumallick

Putz

Pal

2021

IJMS

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In this paper, we present a formulation of highly correlated Fock-space multi-reference coupled-cluster (FSMRCC) methods, including approximate triples on top of the FSMRCC with singles and doubles, which correct the electron affinities by at least at third and up to the fourth order in perturbation. We discuss various partial fourth-order schemes, which are reliable and yet computationally more efficient than the full fourth-order triples scheme. The third-order scheme is called MRCCSD+. We present two approximate fourth-order schemes, MRCCSD+ and MRCCSD+. The results that are presented allow one to choose an appropriate fourth-order scheme, which is less expensive and right for the problem. All these schemes are based on the effective Hamiltonian scheme, and provide a direct calculation of the vertical electron affinities. We apply these schemes to a prototype molecule, using four different basis sets, as well as BeO and CH+. We have calculated the vertical electron affinities of at the geometry of the neutral molecule. We also present the vertical ionization potentials of the anion at the geometry of the anion ground state. We have also shown how to calculate adiabatic electron affinity, though in that case we lose the advantages of direct calculation. BeO has been examined in two basis sets. For CH+, four different basis sets have been used. We have presented the partial fourth-order schemes to the EA in all the basis sets. The results are analyzed to illustrate the importance of triples, as well as highlight computationally efficient partial fourth-order schemes. The choice of the basis set on the electron affinity calculation is also emphasized. Comparisons with available experimental and theoretical results are presented. The general fourth-order schemes, which are conceptually equivalent with the Fock-space multi-reference coupled-cluster singles, doubles, and triplets (MRCCSD+T) methods, based on bondonic formalism, are also presented here in a composed way, for quantum electronic affinity.

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Recent Advances in the Study of Negative‐Ion Resonances Using Multiconfigurational Propagator and a Complex Absorbing Potential

Das

Samanta

2022

ChemPhysChem

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The transient resonances are a challenge to bound state quantum mechanics. These states lie in the continuum part of the spectrum of the Hamiltonian. For this, one has to treat a continuum problem due to electron‐molecule scattering and the many‐electron correlation problem simultaneously. Moreover, the description of a resonance requires a wavefunction that bridges the part that resembles a bound state with another that resembles a continuum state such that the continuity of the wavefunction and its first derivative with respect to the distance between the incoming projectile and the target is maintained. A review of the recent advances in the theoretical investigation of the negative‐ion resonances (NIR) is presented. The NIRs are ubiquitous in nature. They result from the scattering of electrons off of an atomic or molecular target. They are important for numerous chemical processes in upper atmosphere, space and even biological systems. A contextual background of the existing theoretical methods as well as the newly‐developed multiconfigurational propagator tools based on a complex absorbing potential are discussed.

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Shape resonance of sulphur dioxide anion excited states using the CAP-CIP-FSMRCCSD method

Abstract: Aug-cc-pVTZ basis 'box.1266' u 2:3 'box.1166' u 2:3 'box.1066

Cited by 7 publications

References 57 publications

Negative Ion Resonance States: The Fock-Space Coupled-Cluster Way

Negative Ion Resonance States: The Fock-Space Coupled-Cluster Way

Three-Body Excitations in Fock-Space Coupled-Cluster: Fourth Order Perturbation Correction to Electron Affinity and Its Relation to Bondonic Formalism

Recent Advances in the Study of Negative‐Ion Resonances Using Multiconfigurational Propagator and a Complex Absorbing Potential

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