Taking into consideration the overlapping effect of electron clouds between two atoms in a molecule, a modification method is presented which can be used to calculate the total cross sections for electron scattering from numerous molecules at medium and high energies. The modified complex optical potential composed of static, exchange, polarization plus absorption is directly employed to calculate the total cross sections for electron scattering from isoelectronic molecules (HCl, H2S, PH3 and SiH4) over the energy range 30—5000eV using the additivity rule model at Hartree-Fock level. The obtained quantitative molecular total cross sections are compared with those obtained by experiments and other theories wherever available, and good agreement is obtained. It is shown that the additivity rule model together with the modified complex optical potential can give much better results than the unmodified one. So, the modification potential method presented here can improve the accuracy of the total cross section calculations of electron scattering from molecules.
In this paper, we calculate the scattering parameters for collision between potassium and cesium atoms at ultracold temperatures, such as s-wave scattering length, effective range and p-wave scattering length, by the quantum method and semiclassical method, respectively. The singlet and the triplet elastic scattering cross sections between 39K and Cs atoms at ultracold temperatures are dominated by s-wave scattering, and shape resonance occurs with the increase of collision energy. There exist pronounced g-wave and d-wave shape resonances for the singlet and the triplet cross sections, respectively. In addition, s-wave scattering lengths are calculated by using the degenerate internet state approximation for selected hyperfine states of 41KCs.
A complex optical model potential modified by incorporating the concept of bonde d atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the total cross sect ions for electron scattering from methane and chloromethanes(CH4 , CCl4, CHCl3, CH2Cl2 and CH3Cl)over the incident energy r ange 30—5000eV by using additivity rule model at Hartree_Fock level. In the stu dy, the complex optical model potential composed of static, exchange, correlatio n polarization plus absorption contributions uses the bonded_atom concept. The quantitative molecular total cross_section results are compared with the experim ental data and other calculation results wherever available, and good agreement is obtained. It is shown that the additivity rule model together with the comple x optical potential model modified by incorporating the concept of bonded atom c an give better results than that unmodified. So, the introduction of the bonded_ atom concept in the complex optical model potential improves the accuracy of the total cross_section calculation results of electrons from molecules.
Theenergies,equilibriumgeometriesandharmonicfrequenciesofthreeelectronicstates(theground state X 1 撞 + , thefirstdegeneratestate A 1 装 andthesecondstate B 1 撞 +) ofBHmoleculehavebeencalculatedusing theGSUM(groupsumofoperators)methodofSAC/SAC鄄CIwiththebasissetsD95++, 6鄄311++gandcc鄄 PVTZ.Comparingamongtheabovementionedthreebasissets,theconclusionisgainedthatthebasissetcc鄄 PVTZisthemostsuitablefortheenergycalculationofBHmolecule.Thewholepotentialcurvesforthese threeelectronicstatesarefurtherscannedusingSAC/cc鄄PVTZmethodforthegroundstateandSAC鄄CI/cc鄄 PVTZmethodsfortheexcitedstates,thenhaving a leastsquarefittingtoMurrell鄄Sorbiefunction,andlastthe spectroscopyconstants (B e , 琢 e , 棕 e , and 棕 e 字 e) arecalculated,whichareinbetteragreementwiththeexperimental data.ItisbelievedthatMurrell鄄SorbiefunctionformandSAC/SAC鄄CImethodaresuitablenotonlyforthe groundstate,butforthelow鄄lyingexcitedstatesaswell.
Taking into consideration the overlapping effect of electron clouds between two bonded atoms in a molecule, a modificed potential method is presented which can be used to accurately calculate various cross sections for electron scattering by molecules at intermediate and high energies. The modified complex optical potential is directly employed to calculate the absolute differential, elastic integral and moment transfer cross sections for electron scattering by SO2 in the energy range 100—1000 eV by using the additivity rule at Hartree-Fork level. The quantitative results are compared with those obtained by measurement and other theories wherever available. It is shown that the additivity rule model together with the modified complex optical potential can give the encouraging results, which are much closer to the measurements than the unmodified ones.
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