Theoretical molecular structures and electric dipole moments of CCCNH, HCCNC, HCCCNH+, NCNC, and NCCNH+

Molecular structures and energies have been computed at the double zeta SCF level for several linear triple bonded molecules that are either isomers or protonated forms of the familiar molecules cyanoacetylene and cyanogen. These structures have been used to predict rotational constants that can be used as a guide for locating or assigning laboratory or astrophysical microwave spectra. For the same molecules the dipole moments have been computed at the double zeta plus polarization configuration interaction level. Similar structure and dipole moment calculations have also been done on several related known molecules to assess the accuracy of the numerical results. All of the computed dipole moments fit into a pattern that can be roughly explained by simple polarization arguments.