Ab initio calculation of the potential surfaces for low-lying valence electronic states of the C2H radical

Thümmel, Helmar T.; Perić, Miljenko; Peyerimhoff, Sigrid D.; Buenker, Robert J.

doi:10.1007/bf01398898

Cited by 48 publications

(34 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, we refer to the (1,2) conical intersection. A detailed inspection of the non-adiabatic coupling terms revealed the existence of a conical intersection between these two states, for example, at the point fj ¼ 0; r 1 ¼ 1:35 Å , r 2 ¼ 1:60 Å Þ as was established before [105]. More conical intersections of this kind are expected at other r 1 values.…”

mentioning

confidence: 74%

“…(159). To examine our assumption regarding the dependence of s y ðq; yÞ on q, we consider the well-known (collinear) conical intersection of the C 2 H molecule formed by the two lowest states, namely, the 1 2 A 0 and the 2 2 A 0 states [12,72,105]. Figure 9 presents s y ðq; yÞ as calculated for a fixed CÀ ÀC distance, that is, R CC ¼ 1:35 Å and for different q values.…”

Section: The Electronic Non-adiabatic Coupling Termmentioning

confidence: 99%

“…They suggested looking for a symmetric operator that behaves ''violently'' at the vicinity of the conical intersection and use it, instead of the non-adiabatic coupling term, as the integrand to calculate the adiabatic-to-diabatic transformation. Consequently, a series of operators such as the electronic dipole moment operator, the transition dipole moment operator, the quadrupole moment operator, and so on, were employed for this purpose [49,52,53,105]. However, it has to be emphasized that immaterial to the success of this approach, it is still an ad hoc procedure.…”

Section: A Introductory Commentsmentioning

confidence: 99%

See 2 more Smart Citations

The Electronic Non‐Adiabatic Coupling Term in Molecular Systems: A Theoretical Approach

Baer¹

2002

Advances in Chemical Physics

View full text Add to dashboard Cite

mentioning

confidence: 74%

Section: The Electronic Non-adiabatic Coupling Termmentioning

confidence: 99%

Section: A Introductory Commentsmentioning

confidence: 99%

See 1 more Smart Citation

The Electronic Non‐Adiabatic Coupling Term in Molecular Systems: A Theoretical Approach

Baer¹

2002

Advances in Chemical Physics

View full text Add to dashboard Cite

“…Kraemer et al [45] carried out very extensive complete active space self consistent field (CASSCF) calculations on CiH but published only the results for the electronic ground state. For an extensive survey of both the experimental and theoretical studies cited above the reader is referred to [46][47][48][49][50][51][52].…”

Section: Introductionmentioning

confidence: 99%

Analysis and predictions of the vibronic spectrum of the ethynyl radical C2H by ab initio methods

Perić

Peyerimhoff

Buenker

1992

Z Phys D - Atoms, Molecules and Clusters

Self Cite

View full text Add to dashboard Cite

Abstract.A purely ab initio study of the vibronic structure of the C2 H spectrum in the region up to 7000 cm -~, which is complicated by the coupling of the X 2 Z + and A 2H systems, is presented. The potential surfaces for the three lowest-lying electronic states 12A', 22A ' and 12A" correlating with X 2L" + and A 2H at the linear molecular geometry are calculated for the various geometrical distortions by means of the multireference configuration interaction (MRD-CI) method. These adiabatic surfaces are transformed into suitable diabatic counterparts. An approach is developed for a simultaneous treatment of three electronic states coupled via the bending and C-C stretching vibrations. Spin-orbit splitting of the vibronic levels and the vibronically averaged values for the hyperfine coupling constants are computed. The results obtained in this study enable a reliable explanation of the available experimental findings of the C2 H spectrum and predict a number of features to be verified by future experiments.

show abstract

“…The representation of their behavior by means of simple analytic models, as has been done in Section 2, facilitates theoretical treatment. Thus, for these systems an immediate application of this work is in the evaluation of dynamic parameters, like nonadiabatic coupling terms, needed for the dynamic and static properties of some molecules [17,18,21,22]. Some emphasis has been put in this work on the development of the phase during a slow nuclear motion in the vicinity of multiple CIs.…”

Section: Discussionmentioning

confidence: 99%

Experimental and calculational consequences of phases in molecules with multiple conical intersections

Englman

Yahalom

Baer³

et al. 2003

Int J of Quantum Chemistry

View full text Add to dashboard Cite

ABSTRACT:We set up a theoretical model for treating several degeneracies between two adjacent potential energy surfaces in molecular systems, e.g., cases of four (or more) conically intersecting degeneracies, located in a plane formed by two-fold molecular displacement coordinates, in trigonal (or cubic) symmetry and twin conical intersections (CIs) for molecules with two-fold symmetries. When the system circles (in a time-variant manner) entirely inside or entirely outside these CIs, it picks up phases (the geometric phases) that are zero or 2N. Here, N is (to a good approximation) an integer whose value depends on the Hamiltonian for the system, on the distance of circling from the CI, and on the speed of circling. For the adiabatic (slow circling) limit, we develop a simple algebraic-graphical method that yields the value of N in each case. Even in this limit, the value of N is model dependent and is not uniquely given by the number of CIs that are circled. Further, we suggest an experiment (based on a pumpprobe method) for tracing the time development of a system that is subject to a periodically varying field carrying it around the CI. The experiment leads to relations between the spectroscopic transition strengths and state amplitudes, such that the (open-path) phases are fully given (including the additive 2N term and excluding the dynamic phase). Finally, we compare geometric phases that differ by integral multiples of 2 and, therefore, cannot be distinguished by phase interference. We show that the different cases have, nevertheless, observational correlates in the number of times that zero or unity occurs in a wave function component amplitude during circling. The rules of correspondence are given.

show abstract

Ab initio calculation of the potential surfaces for low-lying valence electronic states of the C2H radical

Cited by 48 publications

References 38 publications

The Electronic Non‐Adiabatic Coupling Term in Molecular Systems: A Theoretical Approach

The Electronic Non‐Adiabatic Coupling Term in Molecular Systems: A Theoretical Approach

Analysis and predictions of the vibronic spectrum of the ethynyl radical C2H by ab initio methods

Experimental and calculational consequences of phases in molecules with multiple conical intersections

Contact Info

Product

Resources

About