Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4

Gim, Yeongrok; Lee, Chun‐Woo

doi:10.1063/1.4897564

Cited by 8 publications

(34 citation statements)

References 35 publications

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“…Turning to the excited states, we find that the potential energy curves determined using MSDFT are generally in good agreement with those from MS-CASPT2 as well with those from MRCI studies, 69,71 except for states C and D at short bond distances, where the MSDFT energies are about 0.4 eV higher than the MS-CASPT2 values. This difference may be due to limitations in the basis set used to approximate the Rydberg states or to interactions involving high-energy states that are not included in the VB-localized picture.…”

Section: Resultssupporting

confidence: 74%

“…69–71,73–75 The present MSDFT method does not involve the high cost of a SA-CASSCF computation, but it includes all dynamic correlation at the stage of diabatic (basis) state construction, yielding results comparable or better than the more expensive MS-CASPT2 calculation. Furthermore, the number of configurations in the active space is smaller in the present method (12 determinants vs 45 in the (2,9)-CAS) – an advantage of the DTS scenario).…”

Section: Resultsmentioning

confidence: 99%

“…The global minimum of LiH from MSDFT has a bond length of 1.6 Å with a bond dissociation energy of 2.22 eV, in reasonable agreement with the experimental results (1.596 Å and 2.515 eV) 75 and MS-CASPT2 data (1.588 Å and 2.449 eV) as well as MRCI results (Table 1). 69,71 The small discrepancy (0.3 eV) in bond energy is primarily due to basis set effects in the MSDFT calculation; the deviation is reduced by 0.1 eV if we switch to the aug-cc-pVQZ basis set. Another key energetic quantity is the bond energy relative to the ionic dissociation limit (7.18 eV); this also agrees well with the experimental value (7.15 eV).…”

Section: Resultsmentioning

confidence: 99%

“…LiH is chosen because this simple system provides a challenging case for treating avoided state crossings, spanning a coordinate range from the bonding region to more than 10 Å in interatomic separation, and the states of LiH have been extensively studied both experimentally 71,75 and theoretically so they provide a good case for validation of the present method. 69–71,73,74 …”

Section: Introductionmentioning

confidence: 99%

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Diabatic-At-Construction Method for Diabatic and Adiabatic Ground and Excited States Based on Multistate Density Functional Theory

Grofe

Truhlar

et al. 2017

J. Chem. Theory Comput.

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We describe a diabatic-at-construction (DAC) strategy for defining diabatic states to determine the adiabatic ground and excited electronic states and their potential energy surfaces using the multistate density functional theory (MSDFT). The DAC approach differs in two fundamental ways from the adiabatic-to-diabatic (ATD) procedures that transform a set of preselected adiabatic electronic states to a new representation. (1) The DAC states are defined in the first computation step to form an active space, whose configuration interaction produces the adiabatic ground and excited states in the second step of MSDFT. Thus, they do not result from a similarity transformation of the adiabatic states as in the ATD procedure; they are the basis for producing the adiabatic states. The appropriateness and completeness of the DAC active space can be validated by comparison with experimental observables of the ground and excited states. (2) The DAC diabatic states are defined using the valence bond characters of the asymptotic dissociation limits of the adiabatic states of interest, and they are strictly maintained at all molecular geometries. Consequently, DAC diabatic states have specific and well-defined physical and chemical meanings that can be used for understanding the nature of the adiabatic states and their energetic components. Here we present results for the four lowest singlet states of LiH and compare them to a well-tested ATD diabatization method, namely the 3-fold way; the comparison reveals both similarities and differences between the ATD diabatic states and the orthogonalized DAC diabatic states. Furthermore, MSDFT can provide a quantitative description of the ground and excited states for LiH with multiple strongly and weakly avoided curve crossings spanning over 10 Å of interatomic separation.

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diabatic-At-Construction Method for Diabatic and Adiabatic Ground and Excited States Based on Multistate Density Functional Theory

Grofe

Truhlar

et al. 2017

J. Chem. Theory Comput.

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“…This is confirmed in Figure , as the μ /( n *) 2 vs. R curves converge as n increases. Gim and Lee called these curves reduced DMCs.…”

Section: Dipole Moment Curvesmentioning

confidence: 99%

A Study of 15 Singlet Rydberg Series of HeH and Their Correlation with the Rydberg Series of Li

Kim

Lee

2016

Bulletin Korean Chem Soc

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We theoretically study 37 Rydberg states of HeH derivable from the He(1s 2) + H(nl) configuration with n ≤ 5 along with three states with n = 6. The multireference configuration interaction method is used to calculate their electronic energy curves (EECs) for the internuclear distance R from 0 to 28a 0, which are regarded as the united‐atom (UA) and separated‐atoms (SA) limits, respectively. The 15 Rydberg series (nsσ, npσ, ndσ, nfσ, ngσ, ndδ, nfδ, ngδ, ngγ, npπ, ndπ, nfπ, ngπ, nfϕ, and ngϕ) are identified. Bingel's perturbation theory is used to explain the role of the core part and the Rydberg orbitals in the behavior of EECs at small R. Smith's theory of diabatization is directly solved to obtain the diabatic quantum defect curves (QDCs). From the correlations in diabatic QDCs between the UA and SA limits, the following order of orbital energies in the equilibrium region is found: npσ < nsσ < npπ < ndσ < ndπ < nfσ < nfπ < nfδ < nfϕ < ndδ, except 5dδ < 5fϕ. This order is identical to that in one‐electron molecular systems at small R, except for the nsσ and npπ series. The correlation rules are n UA = n SA + 1 for the npσ series and n UA = n SA for other series; additionally, l UA = l SA for all cases except for the 2pσ − σ1s correlation. A reversal of the diabatic dipole moment at avoided crossing points of the nsσ and npσ series is observed, and explained by the behaviors of ns and np wavefunctions of H at small R.

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Diabatic States at Construction (DAC) through Generalized Singular Value Decomposition

Liu

Chen

Grofe

et al. 2018

J. Phys. Chem. Lett.

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A procedure, called generalized diabatic-at-construction (GDAC), is presented to transform adiabatic potential energy surfaces into a diabatic representation by generalized singular value decomposition. First, we use a set of localized, valence bond-like configuration state functions, called DAC, as the basis states. Then, the adiabatic ground and relevant excited states are determined using multistate density functional theory (MSDFT). GDAC differs in the opposite direction from traditional approaches based on adiabatic-to-diabatic transformation with certain property restraints. The method is illustrated with applications to a model first-order bond dissociation reaction of CH 3 OCH 2 Cl polarized by a solvent molecule, the ground-and first-excited-state potential energy surfaces near the minimum conical intersection for the ammonia dimer photodissociation, and the multiple avoided curve crossings in the dissociation of lithium hydride. The GDAC diabatization method may be useful for defining charge-localized states in studies of electron transfer and proton-coupled electron transfer reactions in proteins.

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Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4

Cited by 8 publications

References 35 publications

Diabatic-At-Construction Method for Diabatic and Adiabatic Ground and Excited States Based on Multistate Density Functional Theory

Diabatic-At-Construction Method for Diabatic and Adiabatic Ground and Excited States Based on Multistate Density Functional Theory

A Study of 15 Singlet Rydberg Series of HeH and Their Correlation with the Rydberg Series of Li

Diabatic States at Construction (DAC) through Generalized Singular Value Decomposition

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