AB-INITIO CALCULATIONS ON MOLECULES OF INTEREST TO INTERSTELLAR CLOUD CHEMISTRY

Making use of CEPA-1, CCSD and CCSD(T) calculations with relatively large basis sets and taking the major anharmonicity effects into account, predictions are made for the following 12 molecules which are of interest to interstellar cloud chemistry: HC3+, H2C3H+, H2CCC, C3N, C2NC, HC2NC, HC2NCH+, HNC3, C5N, C4NC, NC3NC and HC4NC. Four of them (H2CCC, C3N, HC2NC and HNC3) have already been observed both in the laboratory as well as in the interstellar medium. The present predictions may be of help to spectroscopists and radioastronomers in their search for lines of the others.