Ab initio molecular dynamics simulation on SiNÂ +Â CH and SiCÂ +Â NH reactions

The production mechanism for interstellar silicon compounds SiCN, its isomer SiNC, hydrogen cyanide HCN and its isomer HNC from the neutral-neutral reactions SiN + CH and SiC + NH was studied using ab initio molecular dynamics. Classical trajectories were calculated by the direct dynamics simulation technique at the B3LYP/6-311++G(d, p) level of theory. Reaction channels were checked by single-point energy calculations on intermediates and transition states at the B3LYP/6-311++G(3df, 3pd) level of theory and by intrinsic reaction coordinate calculations on reaction coordinates at the B3LYP/6-311++G(d, p) level of theory. More than 100 trajectories were integrated for both reactions. We confirmed that the reaction SiN + CH mostly produces SiNC and HCN, and the reaction SiC + NH mostly produces HNC and SiNH. The reaction processes were examined from the viewpoint of minimum energy path.