Analysis of the rotational spectrum of C3 v molecules by using factorization and diagonalization of the energy matrix : Application to CH 3C 15N

Abstract

A method is given for the analysis of the rotational spectrum in the ground and excited states of C 3 v molecules; it consists in a direct diagonalization of the energy matrix including all elements whose contribution can become significant for the analysis up to the sixth order of approximation. The method of factoring the energy matrix into four submatrices A 1, A 2, E, E, according to the symmetry species of the full point group C 3 v , is given. The programm enables the calculation of the rotational frequencies and also carries out by a least-squares method the fitting of the molecular constants for vibrational states v = 0 (ground state) and v E = 1, 2, 3, and 4, separately or simultaneously over several of these states. The analysis of the rotational spectrum of CH 3C 15N in the v 8 = 0, 1, 2 states is given as an example.