Possibility of ab initio calculation of initial values of parameters for inverse spectral problem

Abstract

It is known, that parameters of spectral lines (half-width, frequency of transitions, intensity, ets) are determined by the solution of inverse spectral problem. Corresponding methods of calculation of parameters of vibration-rotation high resolution spectrum are effective, if two general conditions are fulfilled: 1. The effective Hamiltonian having good extrapolation properties is establ ished. 2. There are enough experimental data to fit the parameters of this Hamiltonian. The first condition is connected with the achievement of theory of effective Hamiltonians and second one is determined by the development of experimental technique. Sometimes the experimental data on some part of spectrum are absent (highly excited vibration-rotation states, electronic excited states). Ab initio calculations of potential energy surfaces of ground and excited electronic states and ab initio determination of vibration states allow us to weaken these difficulties. On the whole, the success of this task is determined by precision of ab initio calculation of electronic energy. The refined optimization method for solving this problem are given bellow.