ABSTRACT: We have employed non-adiabatic molecular dynamics based on time-dependent density-functional theory to characterize the scattering behavior of a proton with the Li4 cluster. This technique assumes a classical approximation for the nuclei, effectively coupled to the quantum electronic system. This time-dependent theoretical framework accounts, by construction, for possible charge transfer and ionization processes, as well as electronic excitations, which may play a role in the non-adiabatic regime. We have varied the incidence angles in order to analyze the possible reaction patterns. The initial proton kinetic energy of 10 eV is sufficiently high to induce non-adiabatic effects. For all the incidence angles considered the proton is scattered away, except in one interesting case in which one of the Lithium atoms captures it, forming a LiH molecule. This theoretical formalism proves to be a powerful, effective and predictive tool for the analysis of non-adiabatic processes at the nanoscale.
Chemical Physics 07/2011; 399:130. · 1.90 Impact Factor
01/2010: pages 299-366; , ISBN: 978-0-444-53440-8
ABSTRACT: A computational study of the dynamics of the charged deuterium trimer D3+ under irradiation by femtosecond laser pulses is presented. The computer simulations are carried out in the frame of a nonadiabatic, nonlinearized model of the coupled evolution of electrons and ions based on the time dependent density functional theory (TDDFT). Several laser field parameters such as intensity, frequency, and polarization have been varied, and their effects on the excitation of the cluster have been analyzed. A proper choice of the laser parameters can be used to lead the trimer across one of the several excitation output channels, from a perturbative regime at low intensities to a nonlinear domain with the occurrence of Coulomb explosion at high intensities.
ABSTRACT: Hydrogen clusters are formed by packing H2 molecules. A
structural characterization of (H2)N clusters up to N=35
has been carried out at zero temperature by using density
functional theory. The binding between the hydrogen molecules is
very weak and the cluster growth reminds that of the inert gas
clusters. An icosahedron is obtained for (H2)13. For
clusters larger than (H2)13 several growth models have
been compared. The binding energy indicates specially stable
clusters for some particular sizes. The magic numbers can be
related to Raman spectroscopy experiments, where the intensity of
the Raman signal serves to assign enhanced abundance to clusters
with N≈13,32,55, which coincide with some of the most
stable clusters obtained in the present study. In addition,
comparison of theory and experiment suggests that clusters with
N smaller than 27 are liquid. The photoabsorption spectra have
been calculated using time-dependent density functional
theory. Those spectra can be interpreted as a widening of the
absorption peaks of the H2 molecule due to the various
environments experienced by different molecules in the same
The European Physical Journal D 01/2007; 43(1):61-64. · 1.48 Impact Factor
The European Physical Journal D 01/2007; 43:61. · 1.48 Impact Factor
ABSTRACT: Experiments of Zweiback et al. Phys. Rev. Lett. 84 2634 (2000)] on the interaction of intense femtosecond laser pulses with a dense molecular beam of large deuterium clusters have shown that these clusters can lose most of their electrons and explode, in a process known as Coulomb explosion. The collisions between the fast deuterium (D) nuclei give rise to D-D fusion. This has motivated us to carry out computer simulations based on the time-dependent density-functional theory in order to understand the ultrafast processes occurring under these high excitations. In particular we have studied the laser irradiation of the singly charged cluster D13+. The simulations show the occurrence of two different cluster fragmentation behaviors, depending on the intensity of the laser pulse: For not too large intensities, the cluster becomes disassembled in a slow way, whereas for large laser intensities substantial ionization takes place and a violent explosion occurs due to the electrostatic repulsion between the nuclei following the loss of the electrons by the cluster. The fast fragmentation mode fits well into the idea of the Coulomb explosion.
Phys. Rev. A. 08/2005; 72(2).