Spectroscopic Characterization of Isomerization Transition States

Baraban, Joshua H.; Changala, P. Bryan; Mellau, Georg Ch.; Stanton, John F.; Merer, A. J.; Field, Robert W.

doi:10.15278/isms.2016.mf07

Cited by 7 publications

(19 citation statements)

References 13 publications

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“…The experimental estimation of the barrier height in ref. 1 differs from the previous ab initio calculations by a significant amount, about 100 cm −1 .…”

Section: Discussioncontrasting

confidence: 71%

“…The HCN/HNC system represents a prototype of isomerisation processes and, also for this reason, has been the subject of several high-resolution spectroscopy studies. Baraban et al 1 and Mellau et al 2 recently studied the [H, C, N] system focusing on one important stationary point -the saddle point. Saddle points are related to chemical processes through transition state theory.…”

Section: Introductionmentioning

confidence: 99%

“…The [H,C,N] system is an ideal candidate to study quantum eigenstates in the neighborhood of a saddle point. 1 Mellau and co-workers were the first to employ experimental spectroscopic methods as a direct probe of transition states and they proposed a general procedure for studying reaction barriers using the properties of the vibrational levels they determined. Mellau and co-workers based their theoretical analysis on the ab initio potential energy surface (PES) of van Mourik et al; 3 however, this surface is not accurate by modern standards, see Harris et al, 4 and improving it is important for future investigations.…”

Section: Introductionmentioning

confidence: 99%

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High Accuracy ab Initio Calculations of Rotational–Vibrational Levels of the HCN/HNC System

et al. 2018

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Highly accurate ab initio calculations of vibrational and rotational-vibrational energy levels of the HCN/HNC (hydrogen cyanide/hydrogen isocyanide) isomerising system are presented for several isotopologues. All-electron multireference configuration interaction (MRCI) electronic structure calculations were performed using basis sets up to aug-cc-pCV6Z on a grid of 1541 geometries. The ab initio energies were used to produce an analytical potential energy surface (PES) describing the two minima simultaneously. An adiabatic Born-Oppenheimer diagonal correction (BODC) correction surface as well as a relativistic correction surface were also calculated. These surfaces were used to compute vibrational and rotational-vibrational energy levels up to 25 000 cm which reproduce the extensive set of experimentally known HCN/HNC levels with a root-mean-square deviation σ = 1.5 cm. We studied the effect of nonadiabatic effects by introducing opportune radial and angular corrections to the nuclear kinetic energy operator. Empirical determination of two nonadiabatic parameters results in observed energies up to 7000 cm for four HCN isotopologues (HCN, DCN, HCN, and HCN) being reproduced with σ = 0.37 cm. The height of the isomerization barrier, the isomerization energy and the dissociation energy were computed using a number of models; our best results are 16 809.4, 5312.8, and 43 729 cm, respectively.

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“…The experimental estimation of the barrier height in ref. 1 differs from the previous ab initio calculations by a significant amount, about 100 cm −1 .…”

Section: Discussioncontrasting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High Accuracy ab Initio Calculations of Rotational–Vibrational Levels of the HCN/HNC System

et al. 2018

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“…The ESQPT in the symmetric phase can be studied using physical quantities such as the effective frequency, defined as ω ef f n, = ∆E n, /∆n [64,65], or the expectation value of the quantum number n in the system eigenstates. The latter quantity acts as an order parameter for the ground state QPT [12].…”

mentioning

confidence: 99%

Anharmonicity-induced excited-state quantum phase transition in the symmetric phase of the two-dimensional limit of the vibron model

Khalouf-Rivera,

Pérez-Bernal,

Carvajal

2021

Preprint

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As already stated in Phys. Rev. A. 81 050101 (2010), the inclusion of anharmonicity into the 2D vibron model in the form of a quadratic bosonic number operator results in a second excited-state quantum phase transition. Such transition, in the classical limit of the model, can be associated with the lowering of the asymptotic energy of the energy functional. We delve into the nature of the new excited-state quantum phase transition and we characterize it in the previously overlooked symmetric phase of the model (also known as cylindrical oscillator or linear phase).

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“…Vibrational spectroscopy is an excellent technique for probing the nature of bonding and identifying chemical structures or phases in the analysis of chemical substances. [1][2][3][4] It has been commonly applied in industrial processes, geochemistry, and health-related chemistry elds. [5][6][7] Experiments have demonstrated that some polar vibrational modes present their vibration wavenumber at different positions in IR and Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

The noncoincidence phenomenon of acetonylacetone CO stretching in a binary mixture and the aggregation-induced split theory

Wang

Liu

et al. 2020

RSC Adv.

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Spectroscopic Characterization of Isomerization Transition States

Cited by 7 publications

References 13 publications

High Accuracy ab Initio Calculations of Rotational–Vibrational Levels of the HCN/HNC System

High Accuracy ab Initio Calculations of Rotational–Vibrational Levels of the HCN/HNC System

Anharmonicity-induced excited-state quantum phase transition in the symmetric phase of the two-dimensional limit of the vibron model

The noncoincidence phenomenon of acetonylacetone CO stretching in a binary mixture and the aggregation-induced split theory

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