Sudden Vector Projection-Driven Stability Prediction in Cyclobutane Nitric Ester Isomers

Predicting the relative stability of energetic isomers is challenging when they exhibit similar reaction energy barriers, as traditional energy-based metrics fail to distinguish them. This study develops the sudden vector projection (SVP) model to resolve these ambiguities by revealing the atom-level vibrational mode specificity that qualitatively illuminates the role of vibrational modes in the decomposition reactivity of five cyclobutane nitric ester isomers. The SVP analysis suggests that O-N stretching serves as a dominant decomposition mode and indicates that certain vibrational modes may play a key role in governing the isomers' relative instability trends. Isomer 1 exhibits product-driven instability due to a vibrationally excited fragment, while isomer 3 possesses high intrinsic reactivity masked by transition-state stabilization. These insights establish the relative stability order as 1 (least stable) < 3 < 2 < 4 < 5 (most stable). Furthermore, coupling SVP with Boltzmann analysis reveals that during the initial decomposition, there is a temperature at which the relative stability of different isomers changes. This work establishes SVP as a powerful tool that provides atomic-level dynamical insights for predicting stability in energetic isomers.