The vibration rotation energy of an electronic state of a diatomic molecule is commonly represented by [E.sub.vJ] = [E.sub.v] + [lambda][B.sub.v] + [[lambda].sup.2][D.sub.v] + [[lambda].sup.3][H.sub.v] + [[lambda].sup.4][L.sub.v] + [[lambda].sup.5][M.sub.v] ..., where [lambda] = J(J + 1), v and J are, respectively, the vibrational and rotational quantum numbers, [E.sub.v] is the pure vibrational energy, [B.sub.v] the rotational constant, and [D.sub.v], [H.sub.v], [L.sub.v] + ...
where [e.sub.0] = [E.sub.v] is the pure vibrational energy, [e.sub.1] = [B.sub.v] is the rotational constant, [e.sub.2] = -[D.sub.v], [e.sub.3] = [H.sub.v], ...
In the supplementary material there are three main files: (1) Read me: Rovib-1 is a program for calculating the rovibrational energy eigenvalues [E.sub.vJ], the rotational constant [B.sub.v], and large order centrifugal distortion constants [D.sub.v], [H.sub.v], [L.sub.v], ...
We present in Table SF7 (Supplementary Material file) the vibrational energy levels [E.sub.v], the rotational constants [B.sub.v], and the centrifugal distortion constants [D.sub.v], [H.sub.v], [L.sub.v] of the of the Morse potential for the molecule CO near dissociation (from v = 41 to v= 81).
The spectra show a rotational progression of lines at positions given by B J'(J' + 1), where only the lowest five J' features are visible (J' = 0 - 4), and B, is the rotational constant for vibrational level v.
(13) we know that for the lowest three vibrational levels the hyperfine degeneracy is lifted by no more than 5 MHz, which is still small compared with the natural width and the rotational constant.
The rotational constants and interatomic distance were determined with high precision, as well as the variation of dipole moment with vibrational state and the dipole derivative.
Precise rotational constants, vibration-rotation interaction constants, quadrupole coupling constant, and electric dipole moment were obtained.
One advantage of this program was that it utilized the ground state rotational constants to simulate rotational spectra.
Their topics include the method of least squares, determining the rotational constants
by the spectroscopy of polyatomic molecules, determining equilibrium structures and potential energy functions for diatomic molecules, and structures averages over nuclear motions.