Numerical techniques for the evaluation of non-adiabatic interactions and the generation of quasi-diabatic potential energy surfaces using configuration interaction methods

Mitrushenkov, Alexander O.; Palmieri, Paolo; Puzzarini, Cristina; Tarroni, Riccardo

doi:10.1080/00268970009483373

Cited by 13 publications

(7 citation statements)

References 33 publications

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“…II, due to the multi-configurational nature of the manifold, the quasi-diabatization scheme we have chosen is then based on the overlap of the electronic wavefunction technique. 5 This iterative technique uses the overlap between the adiabatic and diabatic electronic wavefunctions calculated at the geometries R i and R i − 1 , respectively.…”

Section: Quasi-diabatization Schemementioning

confidence: 99%

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Léonard

Quéré

2012

The Journal of Chemical Physics

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The excited (2)Π electronic states of ZnF have been diabatized in order to simulate the (2)Π ← X(2)Σ(+) vibronic spectrum using a wavepacket propagation technique. The spin-orbit coupling functions within the (2)Π states and between the (2)Π and B(2)Σ(+) states have also been diabatized, as well as the dipole and transition moment functions. As the adiabatic electronic (2)Π states are strongly multi-configurational, the quasi-diabatisation scheme was based on the electronic wavefunction overlap along the reaction coordinate. The procedure leads to a repulsive (2)Π state reaching the first dissociation limit, Zn((1)S(g)) + F((2)P(u)), and a bound one associated with the second limit, Zn((3)P(u)) + F((2)P(u)). The adiabatic electronic potentials and coupling functions have been determined at the multi-reference-configuration-interaction level of theory. The vibrational energies and the spin-orbit splittings are in agreement with early experimental data. The wavepacket propagation approach, coupled with a Prony analysis, allowed also to analyze the resonances and the bound vibronic states of the (2)Π manifold. The (2)Π ← X(2)Σ(+) vibronic spectra have been determined for Ω = 1/2 and 3/2 originating to the v'' = 0 level of the X(2)Σ(+) state.

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Section: Quasi-diabatization Schemementioning

confidence: 99%

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Léonard

Quéré

2012

The Journal of Chemical Physics

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“…Most ab initio calculations of the BODC for systems larger than two-electron problems have been limited to implementations at the Hartree−Fock self-consistent field (SCF) level using either spin-restricted , or unrestricted , wave functions. Recently, however, numerical implementations allowing BODC calculations have been presented that employed multiconfiguration SCF, single-reference configuration interaction (CI), , multireference CI (MRCI), − coupled cluster, and first-order (MP1) [note that although the MP1 correction is zero for the BO energy, it provides a good estimate of the BODC] and second-order (MP2) Møller−Plesset perturbation theory methods. , …”

Section: Bodc Analytical Potentialmentioning

confidence: 99%

Functional Representation for the Born−Oppenheimer Diagonal Correction and Born−Huang Adiabatic Potential Energy Surfaces for Isotopomers of H₃

et al. 2009

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Multireference configuration interaction (MRCI) calculations of the Born-Oppenheimer diagonal correction (BODC) for H(3) were performed at 1397 symmetry-unique configurations using the Handy-Yamaguchi-Schaefer approach; isotopic substitution leads to 4041 symmetry-unique configurations for the DH(2) mass combination. These results were then fit to a functional form that permits calculation of the BODC for any combination of isotopes. Mean unsigned fitting errors on a test grid of configurations not included in the fitting process were 0.14, 0.12, and 0.65 cm(-1) for the H(3), DH(2), and MuH(2) isotopomers, respectively. This representation can be combined with any Born-Oppenheimer potential energy surface (PES) to yield Born-Huang (BH) PESs; herein, we choose the CCI potential energy surface, the uncertainties of which ( approximately 0.01 kcal/mol) are much smaller than the magnitude of the BODC. Fortran routines to evaluate these BH surfaces are provided. Variational transition state theory calculations are presented comparing thermal rate constants for reactions on the BO and BH surfaces to provide an initial estimate of the significance of the diagonal correction for the dynamics.

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“…To estimate the overlap and the non-adiabatic couplings, a bi-orthogonal approach, as implemented at CASSCF level in MOLPRO (see alsoRefs. 22,23,28,29), was applied at the geometry of the transition state.…”

mentioning

confidence: 99%

Outstanding Nobility Observed in Cu5 Clusters Reveals the Key Role of Collective Quantum Effects

Buceta¹,

Huseyinova²,

Cuerva³

et al. 2021

Preprint

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Subnanometer-sized metal clusters often feature a molecule-like electronic structure, which makes their physical and chemical properties significantly different from those of nanoparticles and bulk material. Considering potential applications, there is a major concern about their thermal stability and susceptibility towards oxidation. Cu clusters of only 5 atoms (Cu5 clusters) are first synthesized in high concentration using a new-generation wet chemical method. Next, it is shown that, contrary to what is currently assumed, Cu5 clusters display nobility, beyond resistance to irreversible oxidation, at a broad range of temperatures and oxygen pressures. The outstanding nobility arises from an unusual reversible oxidation which is observed by in situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy on Cu5 clusters deposited onto highly oriented pyrolitic graphite at different oxygen pressures and up to 773 K. This atypical property is explained by a theoretical approach combining different state-of-the-art first principles theories. It reveals the essential role of collective quantum effects in the physical mechanism responsible for the nobility of Cu5 clusters, encompassing a structural ‘breathing’ through concerted Cu–Cu elongations/contractions upon O2 uptake/release, and collective charge transfer as well. A predictive phase diagram of their reversible oxidation states is also delivered, agreeing with the experimental observations. The collective quantum effects responsible of the observed nobility are expected to be general in subnanometer-sized metal clusters, pushing this new generation of materials to an upper level.

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Numerical techniques for the evaluation of non-adiabatic interactions and the generation of quasi-diabatic potential energy surfaces using configuration interaction methods

Cited by 13 publications

References 33 publications

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Functional Representation for the Born−Oppenheimer Diagonal Correction and Born−Huang Adiabatic Potential Energy Surfaces for Isotopomers of H₃

Outstanding Nobility Observed in Cu5 Clusters Reveals the Key Role of Collective Quantum Effects

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Numerical techniques for the evaluation of non-adiabatic interactions and the generation of quasi-diabatic potential energy surfaces using configuration interaction methods

Cited by 13 publications

References 33 publications

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Functional Representation for the Born−Oppenheimer Diagonal Correction and Born−Huang Adiabatic Potential Energy Surfaces for Isotopomers of H3

Outstanding Nobility Observed in Cu5 Clusters Reveals the Key Role of Collective Quantum Effects

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Functional Representation for the Born−Oppenheimer Diagonal Correction and Born−Huang Adiabatic Potential Energy Surfaces for Isotopomers of H₃