CONFIGURATION-INTERACTION CALCULATIONS ON THE X-SIGMA-1+ GROUND-STATE AND LOW-LYING A-PI-1 AND DELTA-1 EXCITED-STATES OF THE PN MOLECULE .1. POTENTIAL-ENERGY CURVE OF THE X-SIGMA-1+ STATE OF PN - MISCELLANEOUS SPECTROSCOPIC OBSERVABLES

A series of multireference configuration interaction (CI) calculations using an extended Gaussian basis set have been performed on the X 1SIGMA+ ground state of the PN molecule in order to accurately determine the potential energy surface in the vicinity of the minimum. With the help of this curve a wide assortment of spectroscopic observables have been computed. The overall agreement with experiment is good. Marked correlation energy effects are found for the electric dipole/quadrupole moments and nitrogen nuclear coupling. Pure rotational excitations calculated by means of the numerical solutions of the radial Schrodinger equation are found to be in quite good agreement with experiment. Average values of the electric dipole moment over the first vibrational levels have been derived and the trend exhibited by the experimental data is well reflected by the theoretical results. Vibrorotational transitions, pure vibrational and vibrorotational lifetimes have also been determined which, to date, have not been determined experimentally.