Global Potential Energy Surface Investigation of Cyanoformaldehyde and Its Conformational Dynamics, Decomposition Pathways, and Water-Involved Bimolecular Reactions

Cyanoformaldehyde [HC(O)CN], a detected interstellar molecule, exhibits potential isomeric transformations that remain incompletely understood. Understanding its conformational flexibility is crucial for predicting its reactivity in interstellar conditions. This study presents a comprehensive investigation of the complete HC(O)CN potential energy surface (PES) using the anharmonic downward distortion following (ADDF) algorithm, enabling exhaustive mapping of EQs, TSs, DCs, and connecting pathways. At the B3LYP-D3(BJ)/def2-TZVP level of theory, our analysis reveals 48 EQs, 152 TSs, and 49 DCs. We identify 80 unique isomerization pathways mediated by TS structures (EQ<i>x</i>-TS<i>n</i>-EQ<i>y</i>), complemented by 34 TS-mediated (EQ<i>a</i>-TS<i>b</i>-DC) and 40 direct (EQ<i>m</i>-DC<i>n</i>) DCs. The multicomponent artificial force induced reaction (MC-AFIR) method is employed to generate stochastic conformational ensembles comprising the most stable isomers in investigations and a single water molecule, enabling systematic analysis of product formation propensities. These findings provide a comprehensive database of conformational relationships, thermodynamic behaviors, and water-involved reactions for HC(O)CN isomers. Our analysis establishes a reference framework for predicting isomer stability, interconversion pathways, and reactivity under various conditions.