Total Cross Sections Of Low-energy Electrons Scattering From H₂O Molecule And Structure And Potential Energy Functions For Excited States Of Li₂ And Na₂ Molecules

Collisions of electrons with water molecules play an important role in a variety of research fields such as astrophysics and atmospheric physics, radiation biology and plasma physics. Knowledge of electron-water collision interactions is concernful for models of radiation damage. In part one of this dissertation, the R-matrix method and the UK molecular R-matrix codes are used to calculate total (integral) cross sections of electrons elastic scattering from H₂O molecule in quite low energy range 4-20eV and the scattering calculations are performed within the fixed-nuclei approximation. Then the effect of radius of R-matrix sphere to the results is discussed. Cross sections are compared with previous result and also experiments and the results are in good agreement with experimental ones.The study of diatomic molecular potential energy functions, especially for the functions of excited states, has been considered a topic worthy of investigation. These functions are needed for any dynamical study of molecules including the rates of simple chemical reactions, molecular beam scattering cross-sections and vibrational and rotational spectroscopy. The potential energy function is needed both for classical and quantum mechanical treatments of this dynamics. Thus in the other part, the potential curves for the ground stated X¹âˆ‘_g⁺, and excited states X¹âˆ‘_u⁺, B¹âˆ_u ,a³âˆ‘_u⁺ and b³âˆ_u of Li₂ molecules are calculated by the keyword GSUM in SAC(symmetry-adapted cluster)/SAC-CI(configuration interaction) method with preferable basis set 6-311+g*, and 6-31+g* basis set for X¹âˆ‘_g⁺, X¹âˆ‘_u⁺, B¹âˆ_u...