Electron-Attachment-Induced DNA Damage: Instantaneous Strand Breaks

Low energy electron-attachment-induced damage in DNA, where dissociation channels may involve multiple bonds including complex bond rearrangements and significant nuclear motions, is analyzed here. Quantum mechanics/molecular mechanics (QM/MM) calculations reveal how rearrangements of electron density after vertical electron attachment modulate the position and dynamics of the atomic nuclei in DNA. The nuclear motions involve the elongation of the P–O (P–O3′ and P–O5′) and C–C (C3′–C4′ and C4′–C5′) bonds for which the acquired kinetic energy becomes high enough so that the neighboring C3′–O3′ or C5′–O5′ phosphodiester bond may break almost immediately. Such dynamic behavior should happen on a very short time scale, within 15–30 fs, which is of the same order of magnitude as the time scale predicted for the excess electron to localize around the nucleobases. This result indicates that the C–O phosphodiester bonds can break before electron transfer from the backbone to the base

Electron-Attachment-Induced DNA Damage: Instantaneous Strand Breaks

Low energy electron-attachment-induced damage in DNA, where dissociation channels may involve multiple bonds including complex bond rearrangements and significant nuclear motions, is analyzed here. Quantum mechanics/molecular mechanics (QM/MM) calculations reveal how rearrangements of electron density after vertical electron attachment modulate the position and dynamics of the atomic nuclei in DNA. The nuclear motions involve the elongation of the P–O (P–O3′ and P–O5′) and C–C (C3′–C4′ and C4′–C5′) bonds for which the acquired kinetic energy becomes high enough so that the neighboring C3′–O3′ or C5′–O5′ phosphodiester bond may break almost immediately. Such dynamic behavior should happen on a very short time scale, within 15–30 fs, which is of the same order of magnitude as the time scale predicted for the excess electron to localize around the nucleobases. This result indicates that the C–O phosphodiester bonds can break before electron transfer from the backbone to the base

Electron-Attachment-Induced DNA Damage: Instantaneous Strand Breaks

Low energy electron-attachment-induced damage in DNA, where dissociation channels may involve multiple bonds including complex bond rearrangements and significant nuclear motions, is analyzed here. Quantum mechanics/molecular mechanics (QM/MM) calculations reveal how rearrangements of electron density after vertical electron attachment modulate the position and dynamics of the atomic nuclei in DNA. The nuclear motions involve the elongation of the P–O (P–O3′ and P–O5′) and C–C (C3′–C4′ and C4′–C5′) bonds for which the acquired kinetic energy becomes high enough so that the neighboring C3′–O3′ or C5′–O5′ phosphodiester bond may break almost immediately. Such dynamic behavior should happen on a very short time scale, within 15–30 fs, which is of the same order of magnitude as the time scale predicted for the excess electron to localize around the nucleobases. This result indicates that the C–O phosphodiester bonds can break before electron transfer from the backbone to the base

Electron-Attachment-Induced DNA Damage: Instantaneous Strand Breaks

Low energy electron-attachment-induced damage in DNA, where dissociation channels may involve multiple bonds including complex bond rearrangements and significant nuclear motions, is analyzed here. Quantum mechanics/molecular mechanics (QM/MM) calculations reveal how rearrangements of electron density after vertical electron attachment modulate the position and dynamics of the atomic nuclei in DNA. The nuclear motions involve the elongation of the P–O (P–O3′ and P–O5′) and C–C (C3′–C4′ and C4′–C5′) bonds for which the acquired kinetic energy becomes high enough so that the neighboring C3′–O3′ or C5′–O5′ phosphodiester bond may break almost immediately. Such dynamic behavior should happen on a very short time scale, within 15–30 fs, which is of the same order of magnitude as the time scale predicted for the excess electron to localize around the nucleobases. This result indicates that the C–O phosphodiester bonds can break before electron transfer from the backbone to the base

Near-Quantitative Agreement of Model-Free DFT-MD Predictions with XAFS Observations of the Hydration Structure of Highly Charged Transition-Metal Ions

First-principles dynamics simulations (DFT, PBE96, and PBE0) and electron scattering calculations (FEFF9) provide near-quantitative agreement with new and existing XAFS measurements for a series of transition-metal ions interacting with their hydration shells via complex mechanisms (high spin, covalency, charge transfer, etc.). This analysis does not require either the development of empirical interparticle interaction potentials or structural models of hydration. However, it provides consistent parameter-free analysis and improved agreement with the higher-<i>R</i> scattering region (first- and second-shell structure, symmetry, dynamic disorder, and multiple scattering) for this comprehensive series of ions. DFT+GGA MD methods provide a high level of agreement. However, improvements are observed when exact exchange is included. Higher accuracy in the pseudopotential description of the atomic potential, including core polarization and reducing core radii, was necessary for very detailed agreement. The first-principles nature of this approach supports its application to more complex systems