Hyperfine-resolved variational nuclear motion spectra of homonuclear diatomic molecules.

The diatomic variational nuclear-motion program duo is extended to calculate hyperfine-resolved spectra of homonuclear diatomic molecules. The hyperfine interactions considered include five nuclear magnetic dipole terms and one nuclear electric quadrupole term. Nuclear-exchange symmetry is explicitly incorporated, and the final hyperfine-resolved parity-adapted Hamiltonian is constructed in a complete angular-momentum basis. After diagonalization of this Hamiltonian, hyperfine-resolved line lists can be generated using transition electric dipole and quadrupole moment curves. To validate the implementation, we apply the extended program to H2 and D2, as well as 14N2 and 14N2+, and compare the calculated results with those from previous experimental and theoretical work and from the perturbative program pgopher; good agreement is obtained in all cases.