Absolute differential, elastic integrated and mqment transfer cross sections for electron-OCS collisions at intermediate and high energies

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between atoms in a molecule, is firstly employed to calculate the absolute differential, elastic integrated and moment transfer cross sections for electron scattering by OCS over the incident energy range from 200 to 1000 eV using the additivity rule model at Hartree-Fock level. The calculated results are compared with those obtained by experiment and other theories wherever available, and good agreement is obtained over a wide energy range. It is shown that the additivity rule model together with the modified potential is completely suitable for calculating the absolute differential, elastic integrated and moment transfer cross sections of electron scattering by molecules such as OCS.

Accurate calculation of the elastic scattering properties of ^7Li atoms at ultralow temperatures

The elastic scattering properties for collisions between two ^7Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X^1 ∑g^＋ and triplet a^3 ∑u^＋ ground states of the Li2, Our calculated values for the scattering lengths α and the effective ranges re are compared with previous ones, and found them to be in good agreement. The scattering lengths are 34.6α0 for the singlet state and -27.6α0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X^1 ∑g^＋ and a^3 ∑u^＋ states.

Elastic scattering of two H(~2S_g) and N(~4S_u) atoms at low temperatures and accurate spectroscopic parameters of NH (X^3Σ^-) radical

This paper reports that the interaction potential for the X3Z- state of NH radical is constructed at the CCSD（T）/ cc-PV6Z level of theory. Using this potential, this paper calculates the spectroscopic parameters （De, Re, ωe, ωeχe, αe and Be） and their values are of 3.578eV, 0.10368nm, 3286.833cm^-1, 78.433cm^-1, 0.6469cm^-1 and 16.6735cm^-1 respectively, which are in excellent agreement with the experiments. Then the total of 14 vibrational states has been found when J=0 by solving the radial Schrodinger equation of nuclear motion. For each vibrational state, the vibrational manifolds are reported for the first time. And last, the total cross sections, s-wave, p-wave and d-wave cross sections are computed for the elastic collisions between two ground-state atoms （hydrogen and nitrogen） at low temperatures. It finds that the total elastic cross sections are dominated by s-wave scattering when the collision energy is below 10^-6a.u. The pronounced shape resonance is found at energy of 6.1 × 10^-6a.u. Calculations have shown that the shape resonance comes from the p-wave contributions.

Elastic electron scattering with formamide-(H_(2)O)_(n) complexes(n=1,2):Influence of microsolvation on the π^(*) and σ^(*) resonances

We report elastic cross sections for low-energy electron scattering with formamide-(H_(2)O)n complexes(n=1,2)in the energy region of 0.01-8 eV.The scattering calculations are performed using the R-matrix method in the static-exchange(SE)approximation.We consider three structures of formamide-H_(2)O and six structures of formamide-(H_(2)O)_(2)in the present work.Our purpose is to investigate effects of water molecules hydrogen-bonding to formamide.We focus on the influence of microsolvation on theπ*andσ*resonances of formamide.The scattering result for complexes shows that the position ofπ*resonance appears at lower or higher energies in the cluster than in the isolated formamide depending on the complex structure and the water role in the hydrogen bonding.We explain this behavior according to the net charge of the solute.It is found that the microsolvation environment has a substantial effect on the width ofπ*resonance.Our results indicate that surrounding water molecules may affect the lifetime of the resonances,and hence the process is driven by the anion state,such as the dissociative electron attachment.

Calculation of the elastic scattering properties for cold and ultracold 39K atoms in a triplet state

The elastic scattering properties for collisions between cold and ultracold 39K atoms in a triplet state are investigated. Based on the recent theoretical and experimental results, the improved hybrid potential is presented for a triplet α3∑u^＋ ground state of K2. Our calculated value of the s-wave scattering length a by using the Numerov method for the triplet state is 79.578α0 and found to be in good agreement with the previous ones. The numbers of bound states are supported by the molecular potential. Pronounced shape resonances appear for the l = 3 partial waves for the α3∑u^＋ state. Furthermore, the s-wave scattering cross section, the total cross section and energy positions of shape resonances for the α3∑u^＋ state are calculated.

Elastic electron scattering with CH_(2)Br_(2)and CCl_(2)Br_(2):The role of the polarization effects

We present elastic electron scattering cross sections with holmethane molecules CH_(2)Br_(2)and CCl_(2)Br_(2)in the lowenergy region ranging from 0.01 e V to 20 e V.The calculations are performed with the R-matrix method in static-exchange plus polarization(SEP)and close-coupling(CC)approximations.The integral,differential,and momentum transfer cross sections are calculated.The convergence of the obtained cross sections is checked at four different levels of SEP approximation.The predicted positions of the resonances agree well with available results.The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed.We find that the polarization has a substantial effect on the cross sections,and this effect becomes even more important for lower impact energies.

Calculation of scattering parameters for ultracold ~6 Li-~7 Li elastic collisions

This paper theoretically studies the elastic scattering properties in a mixture of 6Li and 7Li atoms at cold and ultracold temperatures. Based on the constructed accurate interatomic potential of the triplet state for 6Li7Li mixture by the mass scaling method, it calculates the interspecies s-wave scattering lengths and the p-wave scattering lengths by the variable phase method and the semiclassical method, respectively. The scattering length is in good agreement with the experiment. The partial-wave and total cross sections are also calculated and a rich resonance structure is found.

Calculation of the elastic collision properties of Na and Li atoms at ultracold temperature

This paper firstly reports a theoretical study of elastic scattering properties in a mixture of 23Na and 7Li atoms at cold and ultracold temperatures in detail. Based on the new constructed accurate singlet X1∑g＋ and the triplet a3∑u＋ states interatomic potentials for 23Na7Li mixture, it calculates the scattering lengths and the effective ranges by three computational methods, and obtains good agreements. Using the mass scaling method, it also calculates 23Na6Li scattering lengths and s-wave and total elastic cross sections, whose rich resonance structures were found and interpreted in terms of quasibound diatomic levels trapped behind a centrifugal barrier.

K^- Nucleus Elastic Scattering and Momentum-Dependent Optical Potentials

The K? nucleus differential elastic scattering cross section for 12C and 40Ca at is calculated with three momentum-dependent optical potential models, which are density-dependent, relativistic mean field, and hybrid model, respectively. It is found that the forms of momentum-dependent optical potential models proposed by us are reasonable and gain success in the calculations and the momentum-dependent hybrid model is the best model for the K? nucleus elastic scattering.

Design and Manufacture an Elastic Neutron Scattering Spectrometer at the Dalat Nuclear Reactor

The objective of this study is to design an elastic neutron scattering system according to the angle with a sample using thermal neutron beam at the Dalat Nuclear Reactor (DNR). The system is used for research and training in the field of material structure analysis by neutron scattering and diffraction techniques. It is designed on the basis of inheriting the neutron measurement spectrometer systems at the DNR and the scattered neutron measurement systems in the world. The measuring system, which was installed at the horizontal channel 4 of the DNR, consists of 5-helium-3 detectors and a fully electronic system to record the scatter counts and a mechanical system with the possibility of rotating at 15˚-75˚ angles. The constructed system is tested for evaluation of the accuracy, stability and reliability of the mechanical and electronic systems of moving detectors by angles.

Role of a high ground-state centrifugal barrier in the breakup of the ^(31)Ne nucleus

An analysis of the breakup of the 31 Ne weakly-bound neutron-halo system on a lead target is presented,considering the 2p_(3/2) and 1f_(7/2) ground-state configurations.It is shown that a high centrifugal barrier almost wipes out the breakup channel,thus assimilating the breakup of a weakly-bound system to that of a tightly-bound system,and also reduces the range of the monopole nuclear potential.Consequently,a high centrifugal barrier prevents the suppression of the Coulomb-nuclear interference(CNI) peak by weakening couplings to the breakup channel and reducing the range of the monopole nuclear potential,two main factors that would otherwise suppress such a peak.The present study also identifies couplings to the breakup channel and a long-ranged monopole nuclear potential as the main factors that lead to the suppression of the CNI peak.A low centrifugal barrier together with a Coulomb barrier would also effectively prevent the suppression of the CNI peak in proton-halos as reported in the case of the 8B proton-halo.