Low Energy Electron Attachment to Catechin Sulphate

Low energy electron (LEE) attachment can initiate molecular fragmentation through temporary negative ion states, in which autodetachment competes with nuclear motion toward dissociation. We apply an improved local complex potential time-dependent wavepacket (LCP-TDWP) workflow to catechin sulphate, a metabolically relevant catechin conjugate for which, to our knowledge, no dissociative electron attachment (DEA) study has been reported. The model follows a one dimensional C--O bond extension coordinate, whose fragmentation yields a C5-centered catechin-derived radical and the stable bisulphate anion, HSO 4 - . Neutral and anionic potential energy curves were computed at the CAM-B3LYP/6-311++G(2d,2p) level, and vibrational eigenfunctions were obtained with the Fourier grid Hamiltonian method. The coordinate dependent resonance width was defined by an exponential envelope centered at the Franck--Condon coordinate, a Wigner type energy factor built from the local anion--neutral energy difference, and a smooth switch near the curve crossing. Propagation employed a symmetric split-operator scheme with a 0.1 fs time step for 1.0 ps and a complex absorbing potential (CAP) starting at 7.25 a 0 . The Franck--Condon coordinate and the neutral--anion curve crossing lie at R FC =2.659 a 0 and R cross =3.327 a 0 , respectively. The autocorrelation spectrum shows a doorway feature near 0.4512 eV, whereas the DEA cross section peaks at 1.113 eV with a maximum of 4.608 Mb. The cumulative CAP loss from the initial packet at 1.0 ps is 0.003162 (0.3162%). These results characterize the competition between autodetachment and the chosen dissociation channel.