Showing papers by "Wing-Ki Liu published in 2004"
TL;DR: A new optimization algorithm is introduced that combines the basin-hopping method, which can be used to efficiently map out an energy landscape associated with minima, with the multicanonical Monte Carlo method, that encourages the system to move out of energy traps during the computation.
Abstract: We introduce a new optimization algorithm that combines the basin-hopping method, which can be used to efficiently map out an energy landscape associated with minima, with the multicanonical Monte Carlo method, which encourages the system to move out of energy traps during the computation. As an example of implementing the algorithm for the global minimization of a multivariable system, we consider the Lennard-Jones systems containing 150–185 particles, and find that the new algorithm is more efficient than the original basin-hopping method.
31 citations
TL;DR: In this paper, the potential for selectively controlling the excitation and dissociation of the two bonds of the linear triatomic molecule HCN using short laser pulses was studied, and it was shown that intramolecular vibrational redistribution (IVR) has strong influence on the controlling process: at low excitation level, IVR is slow and it is easy to control either bond, whereas at higher exitation it causes rapid leakage into the unexcited bond, making control more difficult.
Abstract: The potential for selectively controlling the excitation and dissociation of the two bonds of the linear triatomic molecule HCN using short laser pulses is studied. We show that intramolecular vibrational redistribution (IVR) has strong influence on the controlling process: at low excitation level, IVR is slow and it is easy to control the excitation of either bond, whereas at higher exitation, IVR causes rapid leakage into the unexcited bond, making control more difficult. Simple linearly chirped pulses are effective in exciting and dissociating the weaker C-H bond. In an attempt to excite the stronger C-N bond, we found that although linearly chirped pulses can transfer energy to the C-N bond, they cannot compete with the much faster internal energy redistribution, and the C-N bond cannot be dissociated because the weaker C-H bond will always break first. To overcome this problem, we construct an optimization scheme and use it to find pulses that do effect C-N dissociation. These pulses however are very short (less than 0.5 ps) and too intense (with brief peaks in the low 10 1 5 W/cm 2 range) so that the molecule will be ionized before dissociation into neutral fragments can occur.
7 citations