Coupled Channel Optical Method Study For Elastic Collision Process Of Positron-H₂

With the appearance of stable and intensive beams of positrons, the problem of scattering of positrons by atoms and molecules has become an increasingly popular area of study .The investigation of the positron-molecule collision processes plays an essential role in study, the interaction of positron with general matter can afford some information of motion and correlation which the interaction of general matter with general matter can not afford. In addition to its fundament nature, the study of positron-molecule collision is also motivated by its relation to other fields of research and by its technological applications, for example, we calculate the elastic differential cross section of e+-H2 in this paper, and the primary component of atmosphere in Jupiter and Saturn is the hydrogen molecule,and the elastic differential cross section of hydrogen molecule is an important parameter for calculating the input and transfer of energy in Jupiter and Saturn. The combined effort of theory and experiment contributes to advances in the field of positron-molecule collision. The elastic scattering is very important for positron-molecule collision theory at low energies, so a lot of experiments and theory involving positron impact with molecules has been done. Because modeling some environment of collision is very difficult in laboratory presently, so experiment data involving positron with most molecule are very scarce. Although many complex phenomena appear, there are many theoretical methods in low-energy region, such as Kohn variational method[6], R-matrix method[7], Schwinger multichannel method[8] and distributed positron model[9] and so on. To date, elaborate calculations on positron-molecule scattering mostly concentrate on the polarization effect of the target. In the last decade, professor McCarthy of Australia and his coworkers applied Feshbach operator and technology of wave function sepration to develop a complex polarization potential, and add it to the integration equation of momentum-space coupled channel, so coupled channel optical method was developed. They applied this method to the calculation of electron-atom and electron-molecule collision successfully[31]. To test the present theoretical method, we calculated the elastic differential cross section of the scattering of low energies positron(1.36eV,2.72eV,4.08eV,5.44eV) from molecular hydrogen, and compared the present calculation results with the other theoretical results. The present calculation results at 1.36eV lies within the upper and lower limits of the other theoretical results below 600. However, our results above 600 is a little larger than the other theoretical calculations. The present calculation shows the same qualitative shape with the other theoretical results at 2.72eV, but our result is slightly higher than the...