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Dmitri Babikov - One of the best experts on this subject based on the ideXlab platform.
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frozen rotor approximation in the mixed quantum classical theory for Collisional Energy Transfer application to ozone stabilization
Journal of Chemical Physics, 2013Co-Authors: Alexander Teplukhin, Mikhail V Ivanov, Dmitri BabikovAbstract:A frozen-rotor approximation is formulated for the mixed quantum/classical theory of Collisional Energy Transfer and ro-vibrational Energy flow [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)]. Numerical tests are conducted to assess its efficiency and accuracy, compared to the original version of the method, where rotation of the molecule in space is treated explicitly and adiabatically. New approach is considerably faster and helps blocking the artificial ro-vibrational transitions at the pre- and post-Collisional stages of the process. Although molecular orientation in space is fixed, the Energy exchange between rotational, vibrational, and translational digresses of freedom still occurs, allowing to compute ro-vibrational excitation and quenching. Behavior of the Energy Transfer function through eight orders of magnitude range of values and in a broad range of ΔE is reproduced well. In the range of moderate −500 ⩽ ΔE ⩽ +500 cm−1 the approximate method is rather accurate. The absolute valu...
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frozen rotor approximation in the mixed quantum classical theory for Collisional Energy Transfer application to ozone stabilization
Journal of Chemical Physics, 2013Co-Authors: Alexander Teplukhin, Mikhail V Ivanov, Dmitri BabikovAbstract:A frozen-rotor approximation is formulated for the mixed quantum/classical theory of Collisional Energy Transfer and ro-vibrational Energy flow [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)]. Numerical tests are conducted to assess its efficiency and accuracy, compared to the original version of the method, where rotation of the molecule in space is treated explicitly and adiabatically. New approach is considerably faster and helps blocking the artificial ro-vibrational transitions at the pre- and post-Collisional stages of the process. Although molecular orientation in space is fixed, the Energy exchange between rotational, vibrational, and translational digresses of freedom still occurs, allowing to compute ro-vibrational excitation and quenching. Behavior of the Energy Transfer function through eight orders of magnitude range of values and in a broad range of ΔE is reproduced well. In the range of moderate -500 ≤ ΔE ≤ +500 cm(-1) the approximate method is rather accurate. The absolute values of stabilization cross sections for scattering resonances trapped behind the centrifugal threshold are a factor 2-to-3 smaller (compared to the explicit-rotation approach). This performance is acceptable and similar to the well-known sudden-rotation approximation in the time-independent inelastic scattering methods.
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equivalence of the ehrenfest theorem and the fluid rotor model for mixed quantum classical theory of Collisional Energy Transfer
Journal of Chemical Physics, 2013Co-Authors: Alexander Semenov, Dmitri BabikovAbstract:The theory of two seemingly different quantum/classical approaches to Collisional Energy Transfer and ro-vibrational Energy flow is reviewed: a heuristic fluid-rotor method, introduced earlier to treat recombination reactions [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)10.1063/1.3576103], and a more rigorous method based on the Ehrenfest theorem. It is shown analytically that for the case of a diatomic molecule + quencher these two methods are entirely equivalent. Notably, they both make use of the average moment of inertia computed as inverse of average of inverse of the distributed moment of inertia. Despite this equivalence, each of the two formulations has its own advantages, and is interesting on its own. Numerical results presented here illustrate Energy and momentum conservation in the mixed quantum/classical approach and open opportunities for computationally affordable treatment of Collisional Energy Transfer.
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forward backward propagation in the mixed quantum classical theory for the Collisional Energy Transfer
Chemical Physics Letters, 2012Co-Authors: Mikhail V Ivanov, Dmitri BabikovAbstract:Abstract A method of forward–backward propagation is incorporated into the mixed quantum–classical theory for calculations of the Collisional Energy Transfer and ro-vibrational Energy flow in a molecule + quencher encounter. This permits to avoid unphysical behavior of the Energy Transfer function in the range of large impact parameters. A case study is presented on stabilization of the metastable states of ozone in collisions with Ar bath gas.
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mixed quantum classical theory for the Collisional Energy Transfer and the rovibrational Energy flow application to ozone stabilization
Journal of Chemical Physics, 2011Co-Authors: Mikhail V Ivanov, Dmitri BabikovAbstract:A mixed quantum-classical approach to the description of Collisional Energy Transfer is proposed in which the vibrational motion of an energized molecule is treated quantum mechanically using wave packets, while the Collisional motion of the molecule and quencher and the rotational motion of the molecule are treated using classical trajectories. This accounts rigorously for quantization of vibrational states, zero-point Energy, scattering resonances, and permutation symmetry of identical atoms, while advantage is taken of the classical scattering regime. Energy is exchanged between vibrational, rotational, and translational degrees of freedom while the total Energy is conserved. Application of this method to stabilization of the van der Waals states in ozone is presented. Examples of mixed quantum-classical trajectories are discussed, including an interesting example of supercollision. When combined with an efficient grid mapping procedure and the reduced dimensionality approximation, the method becomes very affordable computationally.
Kieran F Lim - One of the best experts on this subject based on the ideXlab platform.
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trajectory simulations of Collisional Energy Transfer in highly excited benzene and hexafluorobenzene
Journal of Chemical Physics, 1995Co-Authors: Thomas Lenzer, Robert G Gilbert, K Luther, J Troe, Kieran F LimAbstract:Quasiclassical trajectory calculations of the Energy Transfer of highly vibrationally excited benzene and hexafluorobenzene (HFB) molecules colliding with helium, argon and xenon have been performed. Deactivation is found to be more efficient for HFB in accord with experiment. This effect is due to the greater number of low frequency vibrational modes in HFB. A correlation between the Energy Transfer parameters and the properties of the intramolecular potential is found. For benzene and HFB, average energies Transferred per collision in the given Energy range increase with Energy. Besides weak collisions, more efficient ‘‘supercollisions’’ are also observed for all substrate–bath gas pairs. The histograms for vibrational Energy Transfer can be fitted by biexponential transition probabilities. Rotational Energy Transfer reveals similar trends for benzene and HFB. Cooling of rotationally hot ensembles is very efficient for both molecules. During the deactivation, the initially thermal rotational distribution heats up more strongly for argon or xenon as a collider, than for helium, leading to a quasi‐steady‐state in rotational Energy after only a few collisions.
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quasiclassical trajectory study of Collisional Energy Transfer in toluene systems ii helium bath gas Energy and temperature dependences and angular momentum Transfer
Journal of Chemical Physics, 1994Co-Authors: Kieran F LimAbstract:The Collisional deactivation of highly vibrationally excited toluene‐d0 and toluene‐d8 by helium bath gas has been investigated using quasiclassical trajectory simulations. Collisional Energy Transfer was found to increase with initial toluene internal Energy, in agreement with the experiments of Toselli and Barker [J. Chem. Phys. 97, 1809 (1992), and references therein]. The temperature dependence of 〈ΔE2〉1/2 is predicted to be T(0.44±0.10), in agreement with the experiments of Heymann, Hippler, and Troe [J. Chem. Phys. 80, 1853 (1984)]. Toluene is found to have no net angular‐momentum (rotational‐Energy) Transfer to helium bath gas, although 〈ΔJ2〉1/2 has a temperature dependence of T(0.31±0.07). Re‐evaluation of earlier calculations [‘‘Paper I:’’ Lim, J. Chem. Phys. 100, 7385 (1994)] found that rotational Energy Transfer could be induced by increasing the mass of the collider, or by increasing the strength of the intermolecular interaction: in these cases, angular‐momentum Transfer depended on the initi...
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quasiclassical trajectory study of Collisional Energy Transfer in toluene systems i argon bath gas Energy dependence and isotope effects
Journal of Chemical Physics, 1994Co-Authors: Kieran F LimAbstract:Experimental studies of Collisional Energy Transfer from highly vibrationally excited toluene to various bath gases have recently been reported [Toselli and Barker, J. Chem. Phys. 97, 1809 (1992), and references therein]. A quasiclassical trajectory investigation for toluene in argon bath gas at 300 K for initial internal energies E’=41 000, 30 000, and 15 000 cm−1 is reported here. Collisional Energy Transfer is almost linearly dependent on E’. Predictions of Energy Transfer quantities are very sensitive to the average well depth of the assumed individual pairwise potentials, but is less sensitive to the detailed shape. Qualitative and quantitative agreement with experiment is obtained where the overall well depth is physically realistic. Isotope studies using 40Ar and pseudohelium (4Ar) bath gases indicate that Energy Transfer is independent of the mass of the bath‐gas collider, but perdeuteration increases 〈ΔE2〉1/2 by 13% over the undeuterated values.
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Collisional Energy Transfer in highly excited molecules calculations of the dependence on temperature and internal rotational and translational Energy
Journal of Chemical Physics, 1992Co-Authors: David L Clarke, Robert G Gilbert, I Oref, Kieran F LimAbstract:Classical trajectory calculations of the rate of Collisional Energy Transfer between a bath gas and a highly excited polyatomic method, and the average Energy Transferred per collision, as functions of the bath gas translational Energy and temperature, are reported. The method used is that of Lim and Gilbert [J. Phys. Chem. 94, 72 (1990)], which requires only about 500 trajectories for convergence, and generates extensive data on the Collisional Energy Transfer between Xe and azulene, as a function of temperature, initial relative translational Energy (E’T), and azulene initial internal Energy (E’). The observed behavior can be explained qualitatively in terms of the Xe interacting in a chattering collision with a few substrate atoms, with the collision duration being much too brief to permit ergodicity but with a general tendency to Transfer Energy from hotter to colder modes (both internal and translational). At thermal energies, trajectory and experimental data show that the root‐mean‐squared Energy tr...
K Luther - One of the best experts on this subject based on the ideXlab platform.
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kinetically controlled selective ionization study on the efficient Collisional Energy Transfer in the deactivation of highly vibrationally excited trans stilbene
Journal of Physical Chemistry A, 2006Co-Authors: Heiko Frerichs, Matthias Hollerbach, Thomas Lenzer, K LutherAbstract:Direct measurements of the gas-phase Collisional Energy Transfer parameters are reported for the deactivation of highly vibrationally excited trans-stilbene molecules, initially prepared with an av...
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pect model analysis and predictions of experimental Collisional Energy Transfer probabilities p e e and moments for azulene and biphenylene
Journal of Physical Chemistry B, 2005Co-Authors: Thomas Lenzer, K Luther, Daniel Nilsson, Sture NordholmAbstract:Experimental Collisional Energy Transfer data from kinetically controlled selective ionization (KCSI) and ultraviolet absorption (UVA) experiments are analyzed in the framework of the partially ergodic collision theory (PECT). Collisions of azulene and biphenylene with different colliders are investigated as case studies. The downward wings of the P(E‘,E) Energy Transfer distributions obtained from the PECT model are fitted to the recently introduced “variable-shape”-exponential 3-parameter functional form of P(E‘,E) obtained from KCSI experiments, P(E‘,E) ∝ exp[−{(E − E‘)/(C0 + C1E)}Y]. The PECT model is able to reproduce the characteristic dependence of the KCSI “shape parameter” Y on the choice of collider, the Energy dependent width of the KCSI P(E‘,E) distributions, described by α(E) = C0 + C1E, and the temperature dependence of the UVA data above room temperature. The statistical approach of PECT obviously captures the essence of large molecule Energy Transfer at chemically significant energies with...
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multiplex detection of Collisional Energy Transfer using kcsfi
Physical Chemistry Chemical Physics, 2005Co-Authors: Heiko Frerichs, Thomas Lenzer, K Luther, Dirk SchwarzerAbstract:A new detection method for obtaining Collisional transition probabilities P(E′,E) of highly vibrationally excited molecules in the gas phase is presented. The technique employs Energy-selective probing of the time-dependent vibrational population distribution by “kinetically controlled selective fluorescence (KCSF)”. We present experimental results for a test system, the Collisional deactivation of toluene by argon, where we use the well-known “kinetically controlled selective ionization (KCSI)” scheme as a reference for comparison. A newly designed setup is employed that allows simultaneous detection of fluorescence and ionization signals under identical experimental conditions (“kinetically controlled selective fluorescence and ionization = KCSFI”). For the system toluene + argon it is demonstrated that KCSF and KCSI yield identical results. A rate-equation model is presented to understand common features and differences of both approaches. The fluorescence detection scheme shows promise for future investigations on Collisional Energy Transfer. The experimental setup is simpler, because it requires no additional ionization wavelength. This will hopefully give access to the P(E′,E) of systems where, e.g., ionization schemes are difficult to implement due to short wavelengths required for the ionization step. A few examples will be outlined briefly.
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on the accuracy of Collisional Energy Transfer parameters for reaction kinetics applications detailed evaluation of data from direct experiments
Physical Chemistry Chemical Physics, 2004Co-Authors: Thomas Lenzer, K LutherAbstract:It is shown that the spread among the various “direct” experimental 〈ΔE〉 data in the literature, so unsatisfactory for their application in chemical kinetics, can be removed consistently. Underlying agreement within very small uncertainties is demonstrated for the case of the much studied Collisional relaxation of highly vibrationally excited azulene. Benchmark experimental data for the Collisional Energy Transfer of highly vibrationally excited azulene obtained by the method of “kinetically controlled selective ionization (KCSI)” (U. Hold, T. Lenzer, K. Luther and A. C. Symonds, J. Chem. Phys., 2003, 119, 11 192) are used for a detailed comparison with earlier measurements employing time-resolved ultraviolet absorption (UVA) and infrared fluorescence (IRF). The experimental UVA and IRF traces are simulated by convolution of the transient vibrational distributions g(E) during relaxation obtained from KCSI measurements with the respective calibration curves of the UVA and IRF experiments. The differences between such simulations and the experimental curves are traced back to non-negligible contributions of azulene self-collisions in the UVA and IRF data. Astonishing quantitative agreement is reached when azulene/bath gas mixing ratios of the corresponding UVA/IRF experiments are fully accounted for in the KCSI simulations. The influence of self-collisions is thus quantitatively assessed as an important source of error in addition to the well-known problem of calibration curve uncertainties in UVA and IRF detection as discussed earlier (T. Lenzer, K. Luther, K. Reihs and A. C. Symonds, J. Chem. Phys., 2000, 112, 4090).
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Collisional Energy Transfer of highly vibrationally excited toluene and pyrazine transition probabilities and relaxation pathways from kcsi experiments and trajectory calculations
Physical Chemistry Chemical Physics, 2001Co-Authors: Uwe Grigoleit, Thomas Lenzer, K Luther, Martin Mutzel, Atsuko TakaharaAbstract:New experimental results for the Collisional Energy Transfer of highly vibrationally excited toluene and pyrazine employing the method of “kinetically controlled selective ionization (KCSI)” are presented. By means of a master equation approach we determine complete and detailed Collisional transition probabilities P(E′,E) for energies up to 50000 cm−1. The same monoexponential representation P(E′,E)∝exp[ − ((E − E′)/α1(E))Y] (for E′⩽E) with a parametric exponent Y in the argument and linearly Energy dependent α1(E) = C0 + C1E successfully used in our earlier investigation [T. Lenzer, K. Luther, K. Reihs and A. C. Symonds, J. Chem. Phys., 2000, 112, 4090] can reproduce the toluene and pyrazine results for the whole range of bath gases studied. The parameters Y, C0 and C1 of P(E′,E) show a smooth increase with the size of the collider. An approximately linear Energy dependence of the first moment of Energy Transfer 〈ΔE〉 is observed for all bath gases. Literature data from infrared fluorescence (IRF) experiments in general show significantly smaller − 〈ΔE〉 values outside the uncertainty limits of the KCSI results. It is shown that this can mainly be traced back to the critical dependence of the IRF data on small uncertainties in the calibration curve. Some of the trends with respect to the Energy Transfer efficiencies of different colliders observed in the KCSI experiments are easily rationalized on the basis of accompanying trajectory calculations on the deactivation of highly vibrationally excited pyrazine by n-propane and CO2. The negligible influence of the V–V relaxation channel in the pyrazine + CO2 system observed in earlier IR diode laser studies is confirmed.
Thomas Lenzer - One of the best experts on this subject based on the ideXlab platform.
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kinetically controlled selective ionization study on the efficient Collisional Energy Transfer in the deactivation of highly vibrationally excited trans stilbene
Journal of Physical Chemistry A, 2006Co-Authors: Heiko Frerichs, Matthias Hollerbach, Thomas Lenzer, K LutherAbstract:Direct measurements of the gas-phase Collisional Energy Transfer parameters are reported for the deactivation of highly vibrationally excited trans-stilbene molecules, initially prepared with an av...
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gas phase Collisional relaxation of the ch2i radical after uv photolysis of ch2i2
Journal of Physical Chemistry A, 2005Co-Authors: Thomas Lenzer, J Schroeder, Kawon Oum, Kentaro SekiguchiAbstract:Transient UV absorption spectra and kinetics of the CH2I radical in the gas phase have been investigated at 313 K. Following laser photolysis of 1−3 mbar CH2I2 at 308 nm, transient spectra in the wavelength range 330−390 nm were measured at delay times between 60 ns and a few microseconds. The change of the absorption spectra at early times was attributed to vibrational cooling of highly excited CH2I radicals by Collisional Energy Transfer to CH2I2 molecules. From transient absorption decays measured at specific wavelengths, time-dependent concentrations of vibrationally “hot” and “cold” CH2I and CH2I2 were extracted by kinetic modeling. In addition, the transient absorption spectrum of CH2I* radicals between 330 and 400 nm was reconstructed from the simulated concentration−time profiles. The evolution of the absorption spectra of CH2I* radicals and CH2I2* due to Collisional Energy Transfer was simulated in the framework of a modified Sulzer−Wieland model. Additional master equation simulations for the co...
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pect model analysis and predictions of experimental Collisional Energy Transfer probabilities p e e and moments for azulene and biphenylene
Journal of Physical Chemistry B, 2005Co-Authors: Thomas Lenzer, K Luther, Daniel Nilsson, Sture NordholmAbstract:Experimental Collisional Energy Transfer data from kinetically controlled selective ionization (KCSI) and ultraviolet absorption (UVA) experiments are analyzed in the framework of the partially ergodic collision theory (PECT). Collisions of azulene and biphenylene with different colliders are investigated as case studies. The downward wings of the P(E‘,E) Energy Transfer distributions obtained from the PECT model are fitted to the recently introduced “variable-shape”-exponential 3-parameter functional form of P(E‘,E) obtained from KCSI experiments, P(E‘,E) ∝ exp[−{(E − E‘)/(C0 + C1E)}Y]. The PECT model is able to reproduce the characteristic dependence of the KCSI “shape parameter” Y on the choice of collider, the Energy dependent width of the KCSI P(E‘,E) distributions, described by α(E) = C0 + C1E, and the temperature dependence of the UVA data above room temperature. The statistical approach of PECT obviously captures the essence of large molecule Energy Transfer at chemically significant energies with...
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multiplex detection of Collisional Energy Transfer using kcsfi
Physical Chemistry Chemical Physics, 2005Co-Authors: Heiko Frerichs, Thomas Lenzer, K Luther, Dirk SchwarzerAbstract:A new detection method for obtaining Collisional transition probabilities P(E′,E) of highly vibrationally excited molecules in the gas phase is presented. The technique employs Energy-selective probing of the time-dependent vibrational population distribution by “kinetically controlled selective fluorescence (KCSF)”. We present experimental results for a test system, the Collisional deactivation of toluene by argon, where we use the well-known “kinetically controlled selective ionization (KCSI)” scheme as a reference for comparison. A newly designed setup is employed that allows simultaneous detection of fluorescence and ionization signals under identical experimental conditions (“kinetically controlled selective fluorescence and ionization = KCSFI”). For the system toluene + argon it is demonstrated that KCSF and KCSI yield identical results. A rate-equation model is presented to understand common features and differences of both approaches. The fluorescence detection scheme shows promise for future investigations on Collisional Energy Transfer. The experimental setup is simpler, because it requires no additional ionization wavelength. This will hopefully give access to the P(E′,E) of systems where, e.g., ionization schemes are difficult to implement due to short wavelengths required for the ionization step. A few examples will be outlined briefly.
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on the accuracy of Collisional Energy Transfer parameters for reaction kinetics applications detailed evaluation of data from direct experiments
Physical Chemistry Chemical Physics, 2004Co-Authors: Thomas Lenzer, K LutherAbstract:It is shown that the spread among the various “direct” experimental 〈ΔE〉 data in the literature, so unsatisfactory for their application in chemical kinetics, can be removed consistently. Underlying agreement within very small uncertainties is demonstrated for the case of the much studied Collisional relaxation of highly vibrationally excited azulene. Benchmark experimental data for the Collisional Energy Transfer of highly vibrationally excited azulene obtained by the method of “kinetically controlled selective ionization (KCSI)” (U. Hold, T. Lenzer, K. Luther and A. C. Symonds, J. Chem. Phys., 2003, 119, 11 192) are used for a detailed comparison with earlier measurements employing time-resolved ultraviolet absorption (UVA) and infrared fluorescence (IRF). The experimental UVA and IRF traces are simulated by convolution of the transient vibrational distributions g(E) during relaxation obtained from KCSI measurements with the respective calibration curves of the UVA and IRF experiments. The differences between such simulations and the experimental curves are traced back to non-negligible contributions of azulene self-collisions in the UVA and IRF data. Astonishing quantitative agreement is reached when azulene/bath gas mixing ratios of the corresponding UVA/IRF experiments are fully accounted for in the KCSI simulations. The influence of self-collisions is thus quantitatively assessed as an important source of error in addition to the well-known problem of calibration curve uncertainties in UVA and IRF detection as discussed earlier (T. Lenzer, K. Luther, K. Reihs and A. C. Symonds, J. Chem. Phys., 2000, 112, 4090).
Mikhail V Ivanov - One of the best experts on this subject based on the ideXlab platform.
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frozen rotor approximation in the mixed quantum classical theory for Collisional Energy Transfer application to ozone stabilization
Journal of Chemical Physics, 2013Co-Authors: Alexander Teplukhin, Mikhail V Ivanov, Dmitri BabikovAbstract:A frozen-rotor approximation is formulated for the mixed quantum/classical theory of Collisional Energy Transfer and ro-vibrational Energy flow [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)]. Numerical tests are conducted to assess its efficiency and accuracy, compared to the original version of the method, where rotation of the molecule in space is treated explicitly and adiabatically. New approach is considerably faster and helps blocking the artificial ro-vibrational transitions at the pre- and post-Collisional stages of the process. Although molecular orientation in space is fixed, the Energy exchange between rotational, vibrational, and translational digresses of freedom still occurs, allowing to compute ro-vibrational excitation and quenching. Behavior of the Energy Transfer function through eight orders of magnitude range of values and in a broad range of ΔE is reproduced well. In the range of moderate −500 ⩽ ΔE ⩽ +500 cm−1 the approximate method is rather accurate. The absolute valu...
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frozen rotor approximation in the mixed quantum classical theory for Collisional Energy Transfer application to ozone stabilization
Journal of Chemical Physics, 2013Co-Authors: Alexander Teplukhin, Mikhail V Ivanov, Dmitri BabikovAbstract:A frozen-rotor approximation is formulated for the mixed quantum/classical theory of Collisional Energy Transfer and ro-vibrational Energy flow [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)]. Numerical tests are conducted to assess its efficiency and accuracy, compared to the original version of the method, where rotation of the molecule in space is treated explicitly and adiabatically. New approach is considerably faster and helps blocking the artificial ro-vibrational transitions at the pre- and post-Collisional stages of the process. Although molecular orientation in space is fixed, the Energy exchange between rotational, vibrational, and translational digresses of freedom still occurs, allowing to compute ro-vibrational excitation and quenching. Behavior of the Energy Transfer function through eight orders of magnitude range of values and in a broad range of ΔE is reproduced well. In the range of moderate -500 ≤ ΔE ≤ +500 cm(-1) the approximate method is rather accurate. The absolute values of stabilization cross sections for scattering resonances trapped behind the centrifugal threshold are a factor 2-to-3 smaller (compared to the explicit-rotation approach). This performance is acceptable and similar to the well-known sudden-rotation approximation in the time-independent inelastic scattering methods.
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forward backward propagation in the mixed quantum classical theory for the Collisional Energy Transfer
Chemical Physics Letters, 2012Co-Authors: Mikhail V Ivanov, Dmitri BabikovAbstract:Abstract A method of forward–backward propagation is incorporated into the mixed quantum–classical theory for calculations of the Collisional Energy Transfer and ro-vibrational Energy flow in a molecule + quencher encounter. This permits to avoid unphysical behavior of the Energy Transfer function in the range of large impact parameters. A case study is presented on stabilization of the metastable states of ozone in collisions with Ar bath gas.
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mixed quantum classical theory for the Collisional Energy Transfer and the rovibrational Energy flow application to ozone stabilization
Journal of Chemical Physics, 2011Co-Authors: Mikhail V Ivanov, Dmitri BabikovAbstract:A mixed quantum-classical approach to the description of Collisional Energy Transfer is proposed in which the vibrational motion of an energized molecule is treated quantum mechanically using wave packets, while the Collisional motion of the molecule and quencher and the rotational motion of the molecule are treated using classical trajectories. This accounts rigorously for quantization of vibrational states, zero-point Energy, scattering resonances, and permutation symmetry of identical atoms, while advantage is taken of the classical scattering regime. Energy is exchanged between vibrational, rotational, and translational degrees of freedom while the total Energy is conserved. Application of this method to stabilization of the van der Waals states in ozone is presented. Examples of mixed quantum-classical trajectories are discussed, including an interesting example of supercollision. When combined with an efficient grid mapping procedure and the reduced dimensionality approximation, the method becomes very affordable computationally.