4,932 research outputs found
Attachment and solvation of the H- dopant: Structure of NenH- and ArnH) cluster from energy-optimizing calculations
No full textLow-energy electron scattering from CS(1Σ): role of short-range forces on the near-threshold resonance.
No full textErratum: Ring-breaking electron attachment to uracil: Following bond dissociations via evolving resonances,
No full textModelling dissociative dynamics of biosystems after metastable electron attachment: the sugar backbones
No full textThe damage induced by radiation in cells is currently described via low-energy attachment
of electrons produced in the biological medium by the primary radiation. Therefore
the corresponding metastable anionic states are obtained in this work from multichannel quantum
calculations which, in the present study, involve β-D-ribose and β-D-deoxyribose
molecular fragments from RNA and DNA structures. The scattering attributes associated
with the resonant processes are derived from the computed total, elastic cross sections
by means of a high-level Breit-Wigner analysis
of the calculated phase shifts. The present procedure is shown to provide a powerful tool for extracting the resonance
parameters from the scattering data even in the presence of broad, overlapping resonances which
typically occur in the resonant dynamics of complicated biosystems after electron attachment effects
Replacement equivalence of H- and Argon in small(Ar)nH- clusters from structure calculations
No full textFollowing electron attachment to CS(1Sigma) with quantum scattering calculations
No full textAbstract: Parameter-free scattering calculations are carried out for the CS ((1)Sigma(+)) molecular target interacting with slow electrons (<10 eV) using a quantum dynamical approach in the molecular reference frame and varying the internuclear distance over a sizeable range of values. The calculations find a resonant state of CS-((2)Pi) in the low-energy region and the resonance is seen to stabilize as a bound CS- molecule when the bond is Stretched beyond the CS equilibrium value, in agreement with existing experiments and calculations. An analysis of the excess, metastable electron is able to show that the initially occupied d pi*-orbital of the molecular resonance evolves into a more localized p-orbital on the sulphur fragment. The results from the calculations are related to the existing experimental data for the title system and to the information we have on the target molecule electron affinity. (C) 2008 Elsevier B.V. All rights reserved
Microsolvation of LiH+ in helium clusters: Many-body effects and additivity models for the interaction forces
No full textThe ab initio calculation of the interaction forces between the LiH+ molecular ion, at its equilibrium geometry, and several He atoms is carried out in order to isolate and assess the importance of many-body contributions in the search for realistic energy and geometry data. The full potential energy surface (PES) with a single helium partner is obtained first by using an aug-cc-pVQZ basis set for He and higher quality ones for Li and H. The calculations were performed at the CAS-SCF plus MRCI level for the lowest potential energy surface over a total of 480 grid points of the two intermolecular Jacobi coordinates, whereas the excited state surface has also been examined in order to exclude the presence of any significant nonadiabatic interaction between the two PESs. A numerical fit of the lower surface is presented and the general physical changes of the ionic interaction when going from the lower to the upper of the two potentials are described and discussed. The fairly limited importance of many-body effects for such systems is seen from further ab initio calculations including several He atoms: our results suggest that, at least in the present case, no strong charge migration occurs after He attachment, and therefore, one could realistically model larger clusters by implementing a sum-of-potentials approach via the presently computed PES
ELECTRON-DRIVEN REACTIONS IN PROTO-PLANETARY ATMOSPHERES: METASTABLE ANIONS OF GASEOUS o-BENZYNE
No full textIn this paper, we present an investigation into low-energy electron scattering (E < 15 eV) processes from a specific benzene-like polyatomic target such as ortho-benzyne, o-C6H4((1)Sigma), in order to gain a better understanding of the effects that possible low-lying metastable electron-attachment states could have on its nuclear fragmentation dynamics. The current importance of the dynamical evolution of this molecule lies in the fact that o-C6H4 is considered to be relevant for the circumstellar synthesis of large polycyclic aromatic hydrocarbons (PAHs), as a precursor for C6H6 production via ion-based ring closure reaction from C2H2. Our parameter-free scattering calculations are performed within the molecular reference frame, where we obtain the metastable anionic states for the nuclear equilibrium configuration and further characterize the properties of such transient anions with respect to those found earlier for the benzene molecule. Our quantum studies indicate that o-C6H4 is a more efficient producer of compact, fairly long-lived anionic intermediates than benzene itself; hence, this should more rapidly enter the chemical reaction cycles of PAHs formation, thereby disappearing from possible direct observation as a stable anion
Modelling fragmentations of aminoacids after resonant electron attachment: quantum evidence of possible -OH detachment
No full text- …
