Quantum dynamics of reaction on the state (original) (raw)
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2003
We present the quantum dynamics of the title reaction using the Gray–Balint–Kurti wave-packet ~WP! method, several NO vibro-rotational levels, product coordinates, and an asymptotic analysis. We calculate accurate reaction probabilities at J50, estimate those at J.0 via a capture model, and discuss the reaction mechanism analyzing the WP time evolution. We also obtain cross sections and rate constants. The potential is barrier-less and thus both probabilities and cross sections do not have a collision-energy ( Ecol) threshold. The probabilities present many sharp resonances, due to the Ecol redistribution on the NNO-internal and N 2-product degrees of freedom. The reaction is stereo-specific and occurs via a bent abstraction mechanism. The cross sections decrease with Ecol , in agreement with the expected behavior for threshold-less reactions. The present values of the rate constant support previous and less accurate calculations, and are in excellent agreement with laboratory exper...
A Quantum Wave Packet Dynamics Study of the N( 2 D) + H 2 Reaction †
The Journal of Physical Chemistry A, 2006
We report a dynamics study of the reaction N( 2 D) + H 2 (V)0, j)0-5) f NH + H using the time-dependent quantum wave packet method and a recently reported single-sheeted double many-body expansion potential energy surface for NH 2 (1 2 A′′) which has been modeled from accurate ab initio multireference configurationinteraction calculations. The calculated probabilities for (V)0, j)0-5) are shown to display resonance structures, a feature also visible to some extent in the calculated total cross sections for (V)0, j)0). A comparison between the calculated centrifugal-sudden and coupled-channel reaction probabilities validate the former approximation for the title system. Rate constants calculated using a uniform J-shifting scheme and averaged over a Boltzmann distribution of rotational states are shown to be in good agreement with the available experimental values. Comparisons with other theoretical results are also made.
Time-dependent quantum study of H(2S) + FO(2Π) → OH(2Π) + F(2P) reaction on the 13A′ and 13A″ states
Journal of Computational Chemistry, 2010
The dynamics of the H( 2 S)+FO( 2 ) → OH( 2 )+F( 2 P) reaction on the adiabatic potential energy surface of the 1 3 A and 1 3 A states is investigated. The initial state selected reaction probabilities for total angular momentum J = 0 have been calculated by using the quantum mechanical real wave packet method. The integral cross sections and initial state selected reaction rate constants have been obtained from the corresponding J = 0 reaction probabilities by means of the simple J-Shifting technique. The initial state-selected reaction probabilities and reaction cross section do not manifest any sharp oscillations and the initial state selected reaction rate constants are sensitive to the temperature.
Jcc, 2010
The dynamics of the H( 2 S)+FO( 2 ) → OH( 2 )+F( 2 P) reaction on the adiabatic potential energy surface of the 1 3 A and 1 3 A states is investigated. The initial state selected reaction probabilities for total angular momentum J = 0 have been calculated by using the quantum mechanical real wave packet method. The integral cross sections and initial state selected reaction rate constants have been obtained from the corresponding J = 0 reaction probabilities by means of the simple J-Shifting technique. The initial state-selected reaction probabilities and reaction cross section do not manifest any sharp oscillations and the initial state selected reaction rate constants are sensitive to the temperature.
The Journal of Chemical Physics, 2006
The reaction N+NO→N2+O was studied by means of the time-dependent real wave-packet (WP) method and the J-shifting approximation. We consider the ground 1A″3 and first excited 1A′3 triplet states, which correlate with both reactants and products, using analytical potential energy surfaces (PESs) recently developed in our group. This work extends our previous quantum dynamics study, and probabilities, cross sections, and rate constants were calculated and interpreted on the basis of the different shapes of the PESs (barrierless 1A″3 and with barrier 1A′3 surfaces, respectively). The WP rate constant (k1) shows a weak dependence on T(200–2500K), as the dominant contribution to reactivity is provided by the barrierless ground PES. There is a good agreement of WP k1 with the measurements and variational transition state theory (VTST) data, and also between the WP and VTST k1(1A″3) results. Nevertheless, there is a large discrepancy between the WP and VTST k1(1A′3) results. Product state ...
The Journal of Chemical Physics, 2007
Time-dependent wave packet quantum scattering (TWQS) calculations are presented for HD+(v=0–3;j0=1)+He collisions in the center-of-mass collision energy (ET) range of 0.0–2.0eV. The present TWQS approach accounts for Coriolis coupling and uses the ab initio potential energy surface of Palmieri et al. [Mol. Phys. 98, 1839 (2000)]. For a fixed total angular momentum J, the energy dependence of reaction probabilities exhibits quantum resonance structure. The resonances are more pronounced for low J values and for the HeH++D channel than for the HeD++H channel and are particularly prominent near threshold. The quantum effects are no longer discernable in the integral cross sections, which compare closely to quasiclassical trajectory calculations conducted on the same potential energy surface. The integral cross sections also compare well to recent state-selected experimental values over the same reactant and translational energy range. Classical impulsive dynamics and steric arguments c...
Quantum wave packet study of S (1 D)+ HD reaction
The time-dependent real wave packet method has been used to study S( 1 D)CHD reaction. State-to-state and state-to-all reactive scattering probabilities for a broad range of energy are calculated at zero total angular momentum. The probabilities for JO0 are estimated from accurately computed JZ0 probabilities by using J-shifting approximation. The integral cross-sections are calculated for a large energy range. q
Seven dimensional quantum dynamics study of the H[sub 2]+NH[sub 2]→H+NH[sub 3] reaction
The Journal of Chemical Physics, 2007
Initial state-selected time-dependent wave packet dynamics calculations have been performed for the H 2 +NH 2 → H+NH 3 reaction using a seven dimensional model on an analytical potential energy surface based on the one developed by Corchado and Espinosa-García ͓J. Chem. Phys. 106, 4013 ͑1997͔͒. The model assumes that the two spectator NH bonds are fixed at their equilibrium values and nonreactive NH 2 group keeps C 2v symmetry and the rotation-vibration coupling in NH 2 is neglected. The total reaction probabilities are calculated when the two reactants are initially at their ground states, when the NH 2 bending mode is excited, and when H 2 is on its first vibrational excited state, with total angular momentum J = 0. The converged cross sections for the reaction are also reported for these initial states. Thermal rate constants and equilibrium constants are calculated for the temperature range of 200-2000 K and compared with transition state theory results and the available experimental data. The study shows that ͑a͒ the reaction is dominated by ground-state reactivity and the main contribution to the thermal rate constants is thought to come from this state, ͑b͒ the excitation energy of H 2 was used to enhance reactivity while the excitation of the NH 2 bending mode hampers the reaction, ͑c͒ the calculated thermal rate constants are very close to the experimental data and transition state theory results at high and middle temperature, while they are ten times higher than that of transition state theory at low temperature ͑T = 200 K͒, and ͑d͒ the equilibrium constants results indicate that the approximations applied may have different roles in the forward and reverse reactions. j tot MK ͑R ,r,ŝ͒ = ͱ 1 2͑1 + ␦ K 0 ␦ k0 ͒ ͓⌽ j 12 j 1 j 2 k 2 J tot MK ͑R ,r,ŝ͒ + p͑− 1͒ J tot +j 12 +j 1 +j 2 +k 2 ⌽ j 12 j 1 j 2 −k 1 J tot M−K ͑R ,r,ŝ͔͒,
The Journal of Chemical Physics, 2006
A procedure for the transformation from reactant to product Jacobi coordinates is proposed, which is designed for the extraction of state-to-state reaction probabilities using a time-dependent method in a body-fixed frame. The method consists of several steps which involve a negligible extra computational time as compared with the propagation. Several intermediate coordinates are used, in which the efficiency depends on the masses of the atoms involved in the reaction. A detailed study of the relative efficiency of using reactant and product Jacobi coordinates is presented for several systems, and simple arguments are found depending on the masses of the atoms involved in the reaction. It is found that the proposed method is, in general, more efficient than the use of product Jacobi coordinates, specially for nonzero total angular momentum. State-to-state reaction probabilities are obtained for Li+ FH → LiF+H and F+HO→ FH + O collisions for several total angular momenta.
Quantum wave packet study of S(1D)+D2→SD+D reaction
Chemical Physics, 2005
S( 1 D) + D 2 ! SD + D reaction has been studied by using a time-dependent quantum real wave packet method. State-to-state and state-to-all reactive scattering probabilities for a broad range of energy are calculated at zero total angular momentum. The state-to-state probabilities show many sharp peaks that ascribed to reactive scattering resonances. The probabilities for J > 0 are estimated from accurately computed J = 0 probabilities by using J-shifting approximation. The integral cross-sections are calculated for a large energy range.