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Ha Vinh Lam Nguyen - One of the best experts on this subject based on the ideXlab platform.
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the effects of proton tunneling 14n quadrupole Coupling and methyl internal rotations in the microwave spectrum of ethyl methyl amine
Journal of Chemical Physics, 2020Co-Authors: Kenneth J Koziol, Wolfgang Stahl, Ha Vinh Lam NguyenAbstract:The spectra of N-ethyl methyl amine, CH3(NH)CH2CH3, were measured using a molecular jet Fourier transform microwave spectrometer in the frequency range of 2 GHz-26.5 GHz. Splittings due to proton inversion tunneling, Coriolis Coupling, 14N quadrupole Coupling, and methyl internal rotation were fully resolved. The experimentally deduced rotational constants are A = 25 934.717(21) MHz, B = 3919.8212(23) MHz, and C = 3669.530(21) MHz. The proton tunneling causes (+) ↔ (-) splittings of about 1980.9 MHz for all c-type transitions between the lowest symmetric and the higher anti-symmetric energy levels. The splittings of the (+) ← (+) and (-) ← (-) levels, mainly influenced by Coriolis Coupling, were also observed and assigned for b-type transitions, yielding the Coupling constants Fbc = 0.3409(71) MHz and Fac = 163.9(14) MHz. The 14N quadrupole Coupling constants were determined to be χaa = 2.788 65(55) MHz and χbb - χcc = 4.630 45(91) MHz. Fine splittings arising from two inequivalent methyl rotors are in the order of 150 kHz, and the torsional barriers are determined to be 1084.62(41) cm-1 for the CH3NH methyl group and 1163.43(80) cm-1 for the CH2CH3 methyl group. The experimental results are in good agreement with those of quantum chemical calculations.
R A Marcus - One of the best experts on this subject based on the ideXlab platform.
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Coriolis Coupling as a source of non rrkm effects in triatomic near symmetric top molecules diffusive intramolecular energy exchange between rotational and vibrational degrees of freedom
Journal of Chemical Physics, 2010Co-Authors: Maksym Kryvohuz, R A MarcusAbstract:A classical theory is proposed to describe the non-RRKM effects in activated asymmetric top triatomic molecules observed numerically in classical molecular dynamics simulations of ozone. The Coriolis Coupling is shown to result in an effective diffusive energy exchange between the rotational and vibrational degrees of freedom. A stochastic differential equation is obtained for the K-component of the rotational angular momentum that governs the diffusion.
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Coriolis Coupling as a source of non rrkm effects in ozone molecule lifetime statistics of vibrationally excited ozone molecules
Journal of Chemical Physics, 2010Co-Authors: Maksym Kryvohuz, R A MarcusAbstract:A theory that describes the non-RRKM (non-Rice-Ramsperger-Kassel-Marcus) effects in the lifetime statistics of activated ozone molecules is derived. The non-RRKM effects are shown to originate due to the diffusive energy exchange between vibrational and rotational degrees of freedom in ozone molecule. The lifetime statistics is found to be intramolecular diffusion controlled at long times. The theoretical results are in good agreement with the direct MD simulations of lifetime statistics.
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theory of fluorescence excitation spectra using anharmonic Coriolis Coupling in s1 and internal conversion to s0 ii application to the channel three problem in benzene for the 14112 band
Journal of Chemical Physics, 1993Co-Authors: Adam Helman, R A MarcusAbstract:Rotational lines in the fluorescence excitation spectra of the 14112 band of the first excited singlet state (S1) of benzene are calculated for various J and K. For this purpose, perturbation theory is used to obtain an "eigenstate" in S1. Internal conversion to S0 via Franck–Condon (FC) factors is then calculated. A search procedure is used to obtain the important contributors to this S1 state and to this internal conversion process S1-->S0 using the perturbation theory coefficients and the FC factors in the evaluation function. At low J, the calculated lines with K=0 are sharp, other lines being broadened and diminished in intensity. The calculated K=0 lines have a linewidth proportional to J(J+1). For high J, the lines with K=J remain sharp, the other lines being broadened and diminished in intensity. These various results are in general agreement with the experimental findings. The onset of channel three in benzene occurs in the present mechanism via anharmonic-Coriolis Coupling in the S1 state plus internal conversion to S0. The calculations suggest that, at low J, parallel Coriolis Coupling causes mixing of the in-plane mode-excited ``light state'' with in-plane modes that are anharmonically coupled to out-of-plane modes.Dark states with certain excited out-of-plane mode contributions possess large FC factors for the internal conversion to S0. At high J, on the other hand, the in-plane modes are coupled directly to these out-of-plane modes by perpendicular Coriolis Coupling. Paths involving two perpendicular Coriolis operators are important at high J in the present calculation—their matrix elements are larger at high J and so they become more competitive relative to purely anharmonic Coupling operators. Such two-Coriolis paths at high J are expected to yield multiple excitation in the out-of-plane modes and further enhance the internal conversion. The perpendicular Coriolis Coupling is least at J=K and so these lines survive at high J. Two-Coriolis operator paths are calculated to be relatively unimportant at low J. The present calculations, using the same electronic matrix element, account for both the low JK = 0 and high JK = J sets of lines being the dominant ones. Aspects regarding further study are discussed.
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theory of fluorescence excitation spectra using anharmonic Coriolis Coupling in s1 and internal conversion to s0 i general formalism
Journal of Chemical Physics, 1993Co-Authors: Adam Helman, R A MarcusAbstract:A treatment of one- or two-photon fluorescence excitation spectra is described using the vibration–rotation Coupling of zeroth order states in the excited electronic state and nonadiabatic Coupling to the ground state. Using perturbation theory, experimental harmonic frequencies, an anharmonic force field, and various theoretical Coriolis Coupling constants, a quasistationary molecular eigenstate in an excited electronic state S1 is first calculated. The S1 eigenstate is then coupled via the nonadiabatic nuclear kinetic energy operator (internal conversion) to rovibronic states in the ground state manifold, the latter states approximated in a simple manner. A search algorithm is used to select the S1 dark states and the S0 states. Both the perturbation theory coefficient and the Franck–Condon factors are employed in the evaluation function used in the search. The results are applied in part II to the channel three problem in benzene.
Ke-li Han - One of the best experts on this subject based on the ideXlab platform.
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Coriolis Coupling effect in molecular reaction dynamics
Annual Reports Section "C" (Physical Chemistry), 2012Co-Authors: Tianshu Chu, Ke-li HanAbstract:In this chapter, we introduce the recent advances in exploring and analyzing the role that Coriolis Coupling played in molecular collision dynamics. For this purpose, both the CC and the CS calculations that with/without Coriolis Couplings are carried out and compared for a series of collision dynamics including nonadiabatic and adiabatic ones. In particular, such investigation under the nonadiabatic collision dynamics has been achieved with our recently developed quantum dynamical methods and codes. We aimed to provide a rather comprehensive and systematic analysis of Coriolis Coupling effect on molecular collisions, which can benefit quantum dynamics calculations and our understanding of reaction dynamics.
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exact and truncated Coriolis Coupling calculations for the s 1d hd reaction employing the ground adiabatic electronic state
Physical Chemistry Chemical Physics, 2010Co-Authors: Huan Yang, Ke-li Han, George C Schatz, Sean C Smith, Marlies HankelAbstract:We present exact quantum differential cross sections and exact and estimated integral cross sections and branching ratios for the title reaction. We employ a time-dependent wavepacket method as implemented in the DIFFREALWAVE code including all Coriolis Couplings and also an adapted DIFFREALWAVE code where the helicity quantum number and with this the Coriolis Couplings have been truncated. Our exact differential cross sections at 0.453 eV total energy, one of the experimental energies, show good agreement with the experimental results for one of the product channels. While the truncated calculation present a significant reduction in the computational effort needed they overestimate the exact integral cross sections.
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exact quantum scattering study of the ne h 2 reaction on a new ab initio potential energy surface
Journal of Chemical Physics, 2010Co-Authors: Peiyu Zhang, Ke-li HanAbstract:We present a new potential energy surface (PES) for the ground state (1(2)A(')) of the chemical reaction Ne+H(2) (+) from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. The quantum reactive scattering dynamics calculation was carried out over the collision energy (E(col)) range of 0.5-1.5 eV based on the new PES. In this work we have taken the Coriolis Coupling (CC) effect into account. The importance of including the CC quantum scattering calculation has been revealed by the comparison between the CC and the centrifugal sudden approximation calculation. The magnitude and profile of the CC total cross sections for v=0 and j=1 over the collision energy range of 0.5-1.5 eV are found to be in good agreement with the available experimental measurements obtained recently by Zhang et al. [J. Chem. Phys. 119, 10175 (2003)] after taking into account the experimental uncertainties.
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Effect of Coriolis Coupling in chemical reaction dynamics
Physical Chemistry Chemical Physics, 2008Co-Authors: Tianshu Chu, Ke-li HanAbstract:It is essential to evaluate the role of Coriolis Coupling effect in molecular reaction dynamics. Here we consider Coriolis Coupling effect in quantum reactive scattering calculations in the context of both adiabaticity and nonadiabaticity, with particular emphasis on examining the role of Coriolis Coupling effect in reaction dynamics of triatomic molecular systems. We present the results of our own calculations by the time-dependent quantum wave packet approach for H + D2 and F(2P3/2,2P1/2) + H2 as well as for the ion–molecule collisions of He + H2+, D− + H2, H− + D2, and D+ + H2, after reviewing in detail other related research efforts on this issue.
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Coriolis Coupling effects in the calculation of state to state integral and differential cross sections for the h d2 reaction
Journal of Chemical Physics, 2007Co-Authors: Tianshu Chu, Ke-li Han, Marlies Hankel, Gabriel G BalintkurtiAbstract:The quantum wavepacket parallel computational code DIFFREALWAVE is used to calculate state-to-state integral and differential cross sections for the title reaction on the BKMP2 surface in the total energy range of 0.4-1.2 eV with D-2 initially in its ground vibrational-rotational state. The role of Coriolis Couplings in the state-to-state quantum calculations is examined in detail. Comparison of the results from calculations including the full Coriolis Coupling and those using the centrifugal sudden approximation demonstrates that both the energy dependence and the angular dependence of the calculated cross sections are extremely sensitive to the Coriolis Coupling, thus emphasizing the importance of including it correctly in an accurate state-to-state calculation. (c) 2007 American Institute of Physics.
Peiyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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state resolved differential and integral cross sections for the ne h2 v 0 2 j 0 neh h reaction
Journal of Chemical Physics, 2016Co-Authors: Hui Wu, Xiaohu He, Peiyu ZhangAbstract:State-to-state quantum dynamic calculations for the proton transfer reaction Ne + H2+ (v = 0–2, j = 0) are performed on the most accurate LZHH potential energy surface, with the product Jacobi coordinate based time-dependent wave packet method including the Coriolis Coupling. The J = 0 reaction probabilities for the title reaction agree well with previous results in a wide range of collision energy of 0.2-1.2 eV. Total integral cross sections are in reasonable agreement with the available experiment data. Vibrational excitation of the reactant is much more efficient in enhancing the reaction cross sections than translational and rotational excitation. Total differential cross sections are found to be forward-backward peaked with strong oscillations, which is the indication of the complex-forming mechanism. As the collision energy increases, state-resolved differential cross section changes from forward-backward symmetric peaked to forward scattering biased. This forward bias can be attributed to the large...
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time dependent wave packet quantum dynamics study of the ne d2 v0 0 2 j0 0 ned d reaction including the Coriolis Coupling
Journal of Physical Chemistry A, 2014Co-Authors: Cuixia Yao, Peiyu ZhangAbstract:The dynamics of the Ne + D2+ (v0 = 0–2, j0 = 0) → NeD+ + D reaction has been investigated in detail by using an accurate time-dependent wave-packet method on the ground 12A′ potential energy surface. Comparisons between the Coriolis Coupling results and the centrifugal-sudden ones reveal that Coriolis Coupling effect can influence reaction dynamics of the NeD2+ system. Integral cross sections have been evaluated for the Ne + D2+ reaction and its isotopic variant Ne + H2+, and a considerable intermolecular isotopic effect has been found. Also obvious is the great enhancement of the reactivity due to the reagent vibrational excitation. Besides, a comparison with previous theoretical results is also presented and discussed.
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Coriolis Coupling effects in o 4s h2 x1σg oh x3σ h 2s reaction and its isotopic variants exact time dependent quantum scattering study
Journal of Physical Chemistry A, 2012Co-Authors: Hongsheng Zhai, Zhixin Duan, Peiyu ZhangAbstract:The time-dependent wave packet quantum method taking into account the Coriolis Coupling (CC) has been employed to investigate the dynamics of O+ + H-2/D-2/HD (v(i) = 0, j(i) = 0) reactions based on an accurate potential energy surface [Martinez et al. J. Chem. Phys. 2004, 120, 4705]. Through the comparison between the results with and without CC, the pronounced CC effects have been revealed in the title reactions. Moreover, the calculated results with the CC method can well reproduce the data of close-Coupling hyperspherical (CCH) exact quantum method. The calculations demonstrate that the CC effects play an important role in the O+ + H-2 system.
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exact quantum scattering study of the ne h 2 reaction on a new ab initio potential energy surface
Journal of Chemical Physics, 2010Co-Authors: Peiyu Zhang, Ke-li HanAbstract:We present a new potential energy surface (PES) for the ground state (1(2)A(')) of the chemical reaction Ne+H(2) (+) from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. The quantum reactive scattering dynamics calculation was carried out over the collision energy (E(col)) range of 0.5-1.5 eV based on the new PES. In this work we have taken the Coriolis Coupling (CC) effect into account. The importance of including the CC quantum scattering calculation has been revealed by the comparison between the CC and the centrifugal sudden approximation calculation. The magnitude and profile of the CC total cross sections for v=0 and j=1 over the collision energy range of 0.5-1.5 eV are found to be in good agreement with the available experimental measurements obtained recently by Zhang et al. [J. Chem. Phys. 119, 10175 (2003)] after taking into account the experimental uncertainties.
Tianshu Chu - One of the best experts on this subject based on the ideXlab platform.
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Coriolis Coupling effect in molecular reaction dynamics
Annual Reports Section "C" (Physical Chemistry), 2012Co-Authors: Tianshu Chu, Ke-li HanAbstract:In this chapter, we introduce the recent advances in exploring and analyzing the role that Coriolis Coupling played in molecular collision dynamics. For this purpose, both the CC and the CS calculations that with/without Coriolis Couplings are carried out and compared for a series of collision dynamics including nonadiabatic and adiabatic ones. In particular, such investigation under the nonadiabatic collision dynamics has been achieved with our recently developed quantum dynamical methods and codes. We aimed to provide a rather comprehensive and systematic analysis of Coriolis Coupling effect on molecular collisions, which can benefit quantum dynamics calculations and our understanding of reaction dynamics.
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Effect of Coriolis Coupling in chemical reaction dynamics
Physical Chemistry Chemical Physics, 2008Co-Authors: Tianshu Chu, Ke-li HanAbstract:It is essential to evaluate the role of Coriolis Coupling effect in molecular reaction dynamics. Here we consider Coriolis Coupling effect in quantum reactive scattering calculations in the context of both adiabaticity and nonadiabaticity, with particular emphasis on examining the role of Coriolis Coupling effect in reaction dynamics of triatomic molecular systems. We present the results of our own calculations by the time-dependent quantum wave packet approach for H + D2 and F(2P3/2,2P1/2) + H2 as well as for the ion–molecule collisions of He + H2+, D− + H2, H− + D2, and D+ + H2, after reviewing in detail other related research efforts on this issue.
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Coriolis Coupling effects in the calculation of state to state integral and differential cross sections for the h d2 reaction
Journal of Chemical Physics, 2007Co-Authors: Tianshu Chu, Ke-li Han, Marlies Hankel, Gabriel G BalintkurtiAbstract:The quantum wavepacket parallel computational code DIFFREALWAVE is used to calculate state-to-state integral and differential cross sections for the title reaction on the BKMP2 surface in the total energy range of 0.4-1.2 eV with D-2 initially in its ground vibrational-rotational state. The role of Coriolis Couplings in the state-to-state quantum calculations is examined in detail. Comparison of the results from calculations including the full Coriolis Coupling and those using the centrifugal sudden approximation demonstrates that both the energy dependence and the angular dependence of the calculated cross sections are extremely sensitive to the Coriolis Coupling, thus emphasizing the importance of including it correctly in an accurate state-to-state calculation. (c) 2007 American Institute of Physics.
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a time dependent wave packet quantum scattering study of the reaction h2 v 0 2 4 6 j 1 he heh h
Journal of Chemical Physics, 2005Co-Authors: Tianshu Chu, Ke-li Han, X N TangAbstract:The quantum scattering dynamics calculation was carried out for the titled reaction in the collision energy range of 0.0–2.4 eV with reactant H2+ in the rotational state j=1 and vibrational states v=0–2, 4, and 6. The present time-dependent wave-packet calculation takes into account the Coriolis Coupling (CC) and uses the accurate ab initio potential-energy surface of Palmieri et al. [Mol. Phys. 98, 1835 (2000)]. The importance of including the CC quantum scattering calculation has been revealed by the comparison between the CC calculation and the previous coupled state (CS) calculation. The CC total cross sections for the v=2, 4, and 6 states show collision energy-dependent behaviors different from those based on the CS calculation. Furthermore, the collision energy dependence of the total cross sections obtained in the present CC calculation only exhibits minor oscillations, indicating that the chance is slim for reactive resonances in total cross sections to survive through the partial-wave averaging. ...