Isotopic effects of the N(2D) + H2 → NH + H reaction: a quantum time-dependent wave packet investigation

Based on the potential energy surface reported by Li and co-workers (J. Comput. Chem. 34 1686–1696 (2013)), the dynamics calculations of N(²D)?+?H₂(v ₀?=?0, j ₀?=?0) reaction and its isotopic variants HD and D₂ are studied using time-dependent wave packet method in the collision energy range of 0.01–1.0?eV. Dynamics properties such as reaction probability, differential cross section, and integral cross section are studied at state-to-state level of theory. Present values are compared with available theoretical and experimental results. The results indicate that the integral cross sections of N(²D)?+?D₂ reaction are in general good agreement with the experimental data at collision energy below 0.15?eV. The rotational state-resolved integral cross sections of N(²D)?+?H₂/HD/D₂ reactions are compared with experimental values for the first time, with the obtained values being in good agreement with the experimental data.     

A quantum wave packet study of three-dimensional inelastic scattering: He—H2

A time-dependent quantum mechanical method has been described to calculate the state-to-state inelastic scattering probabilities for three-dimensional atom—diatom inelastic scattering at the zero total angular momentum. The method utilizes the potentially optimized discrete variable representation (DVR) technique for operating a diatomic Hamiltonian on the wave function and avoids the necessity of repeating many Fourier transformations for this operation. The method has been applied to the He + H₂(v,j)→ He + H₂(v′,j′) inelastic scattering problem.     

Dynamics studies of O+ + D2 reaction using the time-dependent wave packet method

Based on the potential energy surface (PES) reported by Li et al. (Phys. Chem. Chem. Phys. 20, 1039 (2018)), the initial state dynamics calculation of O⁺?+?D₂ (v?=?0, j?=?0) reaction was conducted using the time-dependent wave packet method with a second order split operator. Dynamics properties such as reaction probability, integral cross section, differential cross section, and distribution of products were calculated and compared with available experimental and theoretical results. The present integral cross section values were in good agreement with experimental results. In addition, the differential cross section indicates that the mechanism of the complex-formation reaction plays a dominant role during the reaction.     

Theoretical study on the reaction of CH3CHCl + NO2

The detailed reaction mechanism of 1-chloroethyl radical with NO₂ is investigated theoretically. The results show that the title reaction is more favourable on the singlet potential energy surface than on the triplet one. For the singlet PES of CH₃CHCl?+?NO₂, it is shown that the CH₃CHCl radical can react with NO₂ to barrierlessly generate adduct a (H₃CHClCNO₂), b₁ (H₃CHClCONO-trans), and b₂ (H₃CHClCONO-cis), respectively. A total of six energetically reaction pathways and ten products are found. However, the most competitive path way is P₁ (CH₃CHO?+?ClNO), which can further dissociate to give P₆ (CH₃CHO?+?Cl?+?NO) and P₂ (CH₃CClO?+?HNO). The present results can lead to a deep understanding of the mechanism of the title reaction and may be helpful for understanding the halogenated ethyl chemistry.     

State-to-state quantum dynamics studies of the H + LiH+ → Li+ + H2 reaction

ABSTRACT

Quantum dynamical calculations of the H?+?LiH⁺?→?Li⁺?+?H₂ reaction were performed based on the potential energy surface (PES) reported by Dong et al. (RSC Adv. 7, 7008 (2017)) using the time-dependent quantum wave packet method in collision energy range from 0.01 to 1.0?eV. Dynamics properties such as reaction probability, integral cross section, differential cross section (DCS), and thermal rate constant of the H?+?LiH⁺?→?Li⁺?+?H₂ reaction were reported at the state-to-state level of theory and compared with available theoretical calculations. The results indicated that present values are in good agreement with results obtained from the quasi-classical trajectory method. However, large differences can be found between present values and previous quantum results. This can be attributed to the different PESs used in the calculation and the CS approximation was adopted in previous theoretical studies. In addition, the ‘rebound’ reaction mechanism was proposed in previous theoretical studies in a high collision energy range. However, the DCS scattering signals calculated in the present work indicated that complex-forming and direct abstract reaction mechanisms are dominant in low and high collision energies, respectively.     

A quantum Hamilton–Jacobi proof of the nodal structure of the wave functions of supersymmetric partner potentials

Quantum Hamilton–Jacobi formalism is used to give a proof for Gozzi’s criterion, which states that for eigenstates of the supersymmetric partners, corresponding to the same energy, the difference in the number of nodes is equal to one when supersymmetry (SUSY) is unbroken and is zero when SUSY is broken. We also show that this proof is also applicable to the case, where isospectral deformation is involved.     

A trial wave function to study of the structure of the molecular dd μ ion

This paper provides a new effort to study of the ddμ structure. The present work is numerically performed using a new trial wave function to the ddμ system in configuration of coupled channels. The present results of energies are more accurate than those of our previous work. The obtained results of formation rates are close to results published by Yu.V. Petrov et al. and giving strong indications that the trial wave function is good enough in determining the resonance states of the mentioned ionic molecule.     

Scattered wave packet formalism for open quantum systems: Comparison with the non-Markovian time-dependent Schrödinger equation

Computational comparison is presented between the scattered wave packet formalism and the non-Markovian time-dependent Schrödinger equation (TDSE). These two approaches have been developed to deal with open quantum systems. We employ these methods to study the dynamics of a Gaussian wave packet scattering from the Eckart barrier. It is shown that strongly oscillatory Green functions required in the integration of the non-Markovian TDSE significantly increase computational effort even for one-dimensional problems. Computational results indicate that the scattered wave packet formalism can achieve higher accuracy and can be several orders of magnitude faster than the integration of the non-Markovian TDSE.     

Theoretical study of the stereodynamics of the He＋HD^＋ reaction

This paper investigates the stereodynamics of the reaction He+HD+ by the quasi-classical trajectory(QCT) method using the most accurate AQUILANTI surface [Aquilanti et al 2000 Mol.Phys.98 1835].The distribution P(φr) of dihedral angle and the distribution P(θr) of angle between k and j have been presented at three different collision energies.Four generalized polarization-dependent differential cross-sections(2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21 /dωt) are also calculated.Some interesting results are obtained from the comparison of the stereodynamics of the title reaction at different collision energies.     

A quantum violation of the second law?

An apparent violation of the second law of thermodynamics occurs when an atom coupled to a zero-temperature bath, being necessarily in an excited state, is used to extract work from the bath. Here the fallacy is that it takes work to couple the atom to the bath and this work must exceed that obtained from the atom. For the example of an oscillator coupled to a bath described by the single relaxation time model, the mean oscillator energy and the minimum work required to couple the oscillator to the bath are both calculated explicitly and in closed form. It is shown that the minimum work always exceeds the mean oscillator energy, so there is no violation of the second law.     

A statistical analysis of the wave numbers of triplet rovibronic transitions of the D2 molecule: II. An experimental study of “dubious” lines

The spectral lines whose identification and wave numbers were acknowledged to be dubious in a statistical analysis of all the experimental data on the triplet rovibronic transitions of the D₂ molecule published by now were studied. The capillary-arc discharge spectrum in a D₂-H₂ (9: 1) mixture was measured at p ≈ 6 torr and current density j ≈ 10 A/cm². The wave numbers of 123 lines (of a total of 138 dubious lines) situated in the spectral region accessible to us (430–730 nm) were determined. The error in wave numbers was ≈ 0.06 cm^?1 because of the low intensity of the lines under study and overlap of their contours resulting from fortuitous superpositions of closely lying lines of other band systems (the so-called blending effect). The new wave number values were substantially different from the literature data. These differences were largely caused by random counting and blending errors and, in four instances, erroneous identification of lines in previous works.     

A meshless method of line radial base function study of Gaussian wave packet broadening in few semiconducting mediums: electron–electron interaction effects

In this paper, we have studied the effect of electron–electron interaction on wave packet broadening in different semiconducting mediums in the presence of conduction band non-parabolicity. We have solved the resulting one dimensional fourth order Schrödinger equation by means of a meshless radial base function approach and 2nd order Runge Kutta method. We have compared different semiconducting mediums GaAs, GaN, AlN, InSb and GaSb and showed that in the absence of the electron–electron interaction, the Gaussian wave packet decays with time elapse while in the presence of the electron–electron interaction, the Gaussian wave packet localizes when time increases. Finally, Gaussian wave packet also localizes faster when we increase the electron–electron interaction strength.     

Erratum: Renormalization group study of the A+B→Φ diffusion-limited reaction

A recent argument of Oerding shows that our calculation of the quantity , which determines the amplitude of the asymptotic decay of the particle density in 2<d<4, was in error. Instead it is simply given by =n ₀, the initial density, for uncorrelated initial conditions.     

A study of the low-lying states in 178Hf through the (n, γ) reaction

The nucleus ¹⁷⁸Hf was studied through thermal neutron and averaged resonance neutron capture reactions. The γ-ray and conversion electrons were measured with high resolution spectrometers. A level scheme up to an excitation energy of ∼2.1 MeV was constructed. It includes ∼65 levels, most of which are ordered into 18 rotational bands. The level scheme is complete up to about 1800keV for spins between 2 and 5. The neutron binding energy was established to be at 7626.3 (3) keV. The consistent Q form of the IBA-1 (CQF) was used to describe the low-lying collective γ and K^π = 0⁺ bands. The agreement with the data was found to be excellent for the energies and B(E2) ratios of the ground and γ bands, whereas the agreement was poor for the K^π = 0⁺ bands.     

A study of the role of the Δ-resonance in the reaction 13C(γ,π−)13Ngs

Cross sections for the exclusive photoproduction reaction ¹³C(γ,π⁻)¹³N_gs were measured at energies across the resonance region. To focus on the resonant production mechanism the measurements were carried out at a fixed nuclear momentum transfer of Q = 1 fm⁻¹. For a test of the non-resonant production and of the nuclear transition matrix element, data at Q = 1.25 fm⁻¹ and a differential cross section at 223 MeV photon energy were taken. There are sizeable discrepancies between our measurements and the theoretical predictions.     

Low-pressure line shape study of acetylene transitions in the ν 1 + ν 2 + ν 4 + ν 5 band over a range of temperatures

In this study we have retrieved the self-broadened widths, self-pressure-induced shifts, and Dicke narrowing coefficients for 20 R-branch transitions in the ν₁?+?ν₂?+?ν₄?+?ν₅ band of acetylene. The spectra were recorded using a three-channel diode laser spectrometer, a temperature-controlled cell of fixed length and a second, room temperature cell. The soft collision (Galatry) and hard collision (Rautian) profiles with inclusion of line mixing effects were used to retrieve the line parameters. We determined the temperature dependencies for line broadening, shift, and Dicke narrowing coefficients. We performed comparisons between our retrieved line parameters and published line parameters for acetylene transitions.