TY  - JOUR
A1  - Bouakline, Foudhil
A1  - Lüder, Franziska
A1  - Martinazzo, Rocco
A1  - Saalfrank, Peter
T1  - Reduced and exact quantum dynamics of the vibrational relaxation of a molecular system interacting with a finite-dimensional bath
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - We investigate the vibrational relaxation of a Morse oscillator, nonlinearly coupled to a finite-dimensional bath of harmonic oscillators at zero temperature, using two different approaches: Reduced dynamics with the help of the Lindblad formalism of reduced density matrix theory in combination with Fermi's Golden Rule, and exact dynamics (within the chosen model). with the multiconfiguration time-dependent Hartree (MCTDH) method. Two different models have been constructed, the situation where the bath spectrum is exactly resonant with the anharmonic oscillator transition frequencies, and the case for which the subsystem is slightly off-resonant with the environment. At short times, reduced dynamics calculations describe the relaxation process qualitatively well but fail to reproduce recurrences observed with MCTDH for longer times. Lifetimes of all the vibrational levels of the Morse oscillator have been calculated, and both Lindblad and MCTDH. results show the same dependence of the lifetimes on the initial vibrational state quantum number. A prediction, which should be generic for adsorbate systems is a striking, sharp increase of lifetimes of the subsystem vibrational levels close to the dissociation This is contradictory with harmonic/linear extrapolation laws, which predict a monotonic decrease of the lifetime with initial vibrational quantum number.
Y1  - 2012
U6  - https://doi.org/10.1021/jp304466u
SN  - 1089-5639
VL  - 116
IS  - 46
SP  - 11118
EP  - 11127
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Jankunas, Justin
A1  - Zare, Richard N.
A1  - Bouakline, Foudhil
A1  - Althorpe, Stuart C.
A1  - Herraez-Aguilar, Diego
A1  - Aoiz, F. Javier
T1  - Seemingly anomalous angular distributions in H+D-2 reactive scattering
JF  - Science
N2  - When a hydrogen (H) atom approaches a deuterium (D-2) molecule, the minimum-energy path is for the three nuclei to line up. Consequently, nearly collinear collisions cause HD reaction products to be backscattered with low rotational excitation, whereas more glancing collisions yield sideways-scattered HD products with higher rotational excitation. Here we report that measured cross sections for the H + D-2 -> HD(v' = 4, j') + D reaction at a collision energy of 1.97 electron volts contradict this behavior. The anomalous angular distributions match closely fully quantum mechanical calculations, and for the most part quasiclassical trajectory calculations. As the energy available in product recoil is reduced, a rotational barrier to reaction cuts off contributions from glancing collisions, causing high-j' HD products to become backward scattered.
Y1  - 2012
U6  - https://doi.org/10.1126/science.1221329
SN  - 0036-8075
VL  - 336
IS  - 6089
SP  - 1687
EP  - 1690
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  -