- 第3日 6月24日（金） P会場（501，502，503）
Global exploration of six model chemical’s fragmentation channels on their quantum chemical potential energy surfaces were performed with the scaled hypersphere search/anharmonic downward distortion following (SHS/ADDF)1,2) or the single-component artificial force induced reaction (sc-AFIR)3) at the level of RB3LYP-D3/6-31G(d,p)//PM6-D3 or RB3LYP-D3/6-31+G(d,p)//PM6-D3. The fragmentation channels of the model chemicals, which have been revealed in literature by using stable isotope-labeled reagents, were tested with SHS/ADDF method in this study. The SHS/ADDF gave 1,145 equilibrium (EQ), 1,415 transition-state (TS) and 220 dissociation channel (DC) structures in total. All the major product ions were successfully found by the SHS/ADDF except for deprotonated 4-cyanobutanoic acid. Thus, the sc-AFIR was adopted for its fragmentation reaction, providing 107 EQ, 109 TS and 30 DC structures. Among them, a proper structure of the product ions, which could be seen on its mass spectrum, were found. All the found fragmentation channels were tested by the intrinsic reaction coordinate calculations to confirm that the found structures (EQ of precursor ion, TS and EQs of both product ion and neutral loss) are connected in series. The collision energy values were seen in the literature only for acetaminophen (15 eV) and uracil (25 eV). Their energy barriers were lower than those.