High level ab initio structural and spectroscopic studies of interstellar ion-molecule complexes and interstellar triatomic molecules

C. Eric Cotton, Purdue University

Abstract

Ion molecule complexes are considered possible novel intermediates in the molecular complexification of the interstellar medium. This study reports the results of calculations on the CO, CS, PN, HCN, and HNC molecules and the HCO+, HCS+, HPN+, and HNCH+ ions and their ion-molecule complexes, CO-HCO +, SC-HCS+, and PN-HNP+, HCN-HCNH +, HNC-HCNH+, and HCN-HNCH+. Results from calculations on the triatomic molecules HNSx, HSN x, HPSx, and HNSx (x = -1, 0 , +1) and their low lying electronic excited states are reported. Binging energies of the complexes are found to be significant, implying that these complexes may be observable. It is also found that the interaction of HNC with HNCH+ leads to a novel barrierless isomerization pathway for HNC to HCN. Structural and spectroscopic results from the highly correlated CCSD(T)/aug-cc-pV(6+d)Z and the explicitly correlated CCSD(T)-F12/VQZ-F12 calculations are within 1% when compared to available experimental values. Essential structural and spectroscopic properties for ions and molecules as well as ion-molecule complex are reported. This study provides evidence of novel intermediates and triatomic molecules that can be included in the molecular pathways that constitute the chemical models describing molecular complexification in the interstellar medium.

Degree

Ph.D.

Advisors

Francisco, Purdue University.

Subject Area

Physical chemistry|Astrophysics

COinS