Time-dependent density-functional-theory investigation of the collisions of protons and α particles with uracil and adenine

Abstract

Time-dependent density functional theory was employed to study the e↵ects of proton and ↵-particle radiation on uracil and adenine. This method has the advantage of treating nuclear motion and electronic motion simultaneously, allowing for the study of electronic excitation, charge transfer, ionization, and nuclear motion. Particle energies were surveyed in the range of 15-500 keV for protons and 100-2000 keV for ↵-particles in conjunction with impact points both on and o↵ carbon bonds in order to investigate the electron and nuclear dynamics of irradiated molecules and the form and quantity of transferred energy. The stopping power, energy transferred, and ionization were found and the relationship between incident particle energy and electron density of to the target molecule was characterized for proton and ↵-particle radiation incident on adenine and uracil.

Interactions of Single Particle with Organic Matters: A Facile Bottom-Up Approach to Low Dimensional Nanostructures

“…Based on the measurement of cross-sectional trace of the nanowires by AFM, the radial distribution of crosslinks in the nanowires is discussed in terms of r, defined as the radius of the cross-section. This strongly supports the hypothesis of theoretical Equation (41), where the value of r is determined primarily by the molecular weight of the target polymer, the values of G(x), and S.…”

“…Upon extension of the SPNT to a wider range of polymeric systems with a variety of backbone structures, some discrepancy was found between predicted and measured values of r respectively by Equation (41) and the direct AFM traces. For instance in case of polysilane, using the reported value of G(x) = 0.12 derived from radiation-induced changes in molecular weight, the values of r calculated by Equation (41) were compared with the experimental values, showing a good consistency with the experimental values for polymers with sufficient chain length (M n > 10 4 kg mol −1 ).…”

“…In the most recent cases, the steps were divided into 2 at, revealing gradual changes of the energy state of each target molecule [35]. In this regard, further detailed models were developed rapidly in sequence, taking self-consistent, non-perturbative, and time-lapse treatment of electron dynamics into account for metals [36][37][38], semiconductors [39,40], and biomolecules [41,42]. The origin of the organic molecules on Earth, eventually "D'où venons-nous?…”

Proton-impact-induced electron emission from biologically relevant molecules studied with a screened independent atom model

“…The IAM-PCM is based on a geometrical interpretation of a molecular total cross section as the combined area of overlapping circles which represent atomic cross sections. The latter are calculated from first principles using accurate atomic potentials and the nonperturbative scaled with (7) fit based on (11) TC-BGM for orbital propagation. Once these cross sections have been computed, the IAM-PCM procedure to assemble the molecular cross section is computationally inexpensive and numerically accurate.…”

“…While progress has been made on both experimental (see [2][3][4][5][6][7][8][9] for proton-impact collisions) and theoretical [10][11][12] fronts, the complexity and multitude of molecules of interest suggest that there is a role to be played by simplified models which are easily applicable to a wide range of collision systems.…”