Study Of Special Potential Function Of Diatomic Molecules And Atomic Potential In A Field

The interaction of all kind of particles is always one important field of investigation of atomic and molecular physics. A front part of this paper is special potential function of diatomic molecules, and the other is atomic potential in a field.Molecular potential energy function is complete description of electronic structure. From potential energy function, not only molecular energy, structure and constants of force and spectroscopy but also molecular data of spectroscopy and structure provided for some high and new-technology industries, such as spaceflight, laser, material and so on, can be obtained. So it is important and full of meaning to study the correct representation of potential energy. The study of diatomic molecular potential energy function is the basic problem because diatomic potentials depend on only a single variable, the interatomic distance. Current studies almost focus on the general potential energy functions that have only a minimum. But the studies for especial potential energy functions that have double minimum or a maximum are very few.In the first four sections of this paper, these basic knowledge and calculational methods for the study of potential energy function are simply introduced. 9-parameter Murrell-Sorbie analytical potential energy function that can accurately describe especial potential energy function of diatomic molecule is obtained through calculations and analysis for the first time. The SAC(Symmetry Adapted Cluster)/SAC-CI (Configuration Interaction) method is applied to scan the potential curves for B¹Î£⁺ and b³Î£⁺ states that have double minimum of BH molecule with cc-pVDZ basis set, respectively. Then the scanned results are fitted to 9-paramete Murrell-Sorbie function and the fitted results are good agreement with those scanned results. In order to validate the nicety of 9-parameter Murrell-Sorbie analytical potential energy function, the fitted results are applied to calculate these spectroscopy constants and force constants for B¹Î£⁺ and b³Î£^- states of BH molecule and these calculation results are compared with experiments. These comparison show that all calculation results, such as dissociation energy, equilibrium internuclear distance and rotation-vibration constants, are better agreement with experimental results than other theoretical ones. All these phenomena indicate that 9-parameter Murrell-Sorbie analytical potential energy function can truly describe especial potential energy curve of diatomic molecule. The potential energy curve of B1Π_u state of Li₂ molecule has a maximum and is also an especial one. So the same method is applied to calculate the potential energy curve of B¹Î _u state except with D95(d) basis set. And the result is same as the front.For the universality of 9-parameter Murrell-Sorbie analytical potential energy function, some general potential energy functions, such as the ground state(X¹Î£⁺), C'¹Î”state of BH molecule and the ground state(X¹Î£_g⁺ of Li₂ molecule, are also calculated at the same time. And all the calculation results are excellent.In the fifth section, the research aim is the atomic potential model in a laser field. With the advent of lasers, physicists have been supplied with strong sources of coherent radiation which are now available in the frequency range between the far infrared and, at present, up to the vacuum-ultraviolet(VUV) and soft X-ray region. Atomic and molecular studies in a laser field appeard with the rapid development of powerful laser surces. The studies of these problems are fundamental to our understanding of aspects of atmospheric physics, astrophysics and plasmas. Meanwhile the thorough studies of these processes possess important theoretical meaning in exposing the interaction between electron, photon and atom. The describing of atomic potential in a laser field is of fundamental importance in these studies.Firstly, some fundamental knowledge, such as the describing of laser field, the Kind of electron-atom scattering in a laser field, and so on, are introduced. Then a compution method which is called the Second-order Born approximation and is used to calculate the cross section of electron-atom scattering in a laser field, is provided. In order to validate the correctness, the absolute differential cross sections of e-Ar scattering with multi-photon exchange in some special scattering geometries are calculated with Yukawa potential by applying the Second-order Born approximation and low-frequency approximation theory, respectively. These calculation results indicate that the Second-order Born approximation is available on researching the electron-atom scattering in a laser field. So the absolute differential cross sections of e-Ar scattering are calculated with some different potential models by applying the Second-order Born approximation theory, respectively. And the calculation results are compared with experiments. The importance of exchange potential in the scattering process is given for the first time. And the followings are the conclusions. (a) The optical potential model can preferably describe the atomic potential in a laser. Because the optical potential model includes not only static potential and polarization potential, but also exchange potential that is not included in the general potential model, and the contribution of polarization and exchange potential is not neglected in the total potential, the optical potential model is better than other potential model. (b) The Second-order Bora approximation is available on researching the electron-atom scattering in a laser field.Finally, the total conclusion and later research aim in these directions are given.