Selective excitation of the molecular rotational wave packet by two time-delayed laser pulses

In this paper, we investigate the control of the molecular wave packet of a linear molecule by two femtosecond laser pulses. It is shown that the odd and the even rotational wave packets created by a single laser pulse can be selectively excited by accurately controlling the time delay of another laser pulse. By inserting the peak of the second laser pulse at the position of maximum or minimum value around quarter or three quarter rotational period of the slope curve with odd （or even） rotational wave packet contribution that is created by the first laser pulse, the odd rotational wave packet can be enhanced （or suppressed） while the even rotational wave packet is suppressed （or enhanced）. As a result, the molecular alignments around quarter and three quarter rotational periods can be obtained. Moreover, it is also shown that by inserting the second laser pulse around the quarter or three quarter rotational periods, the changes in the maximum degree of the molecular alignment for the odd and the even rotational wave packet contributions are consistent with their corresponding slope curves at these positions.

Structural, Electronic Properties and Chemical Bonding of Borate Li4CaB2O6 under High Pressure： an Ab Initio Investigation

We calculate structural, electronic properties and chemical bonding of borate Li4CaB2O6 under high pressure by means of the local density-functional pseudopotential approach. The equilibrium lattice constants, density of states, Mulliken population, bond lengths, bond angles as well as the pressure dependence of the band gap are presented. Analysis of the simulated high pressure band structure suggests that borate Li4CaB2O6 can be used as the semi-conductor optical material. Based on the Mulliken population analysis, it is found that the electron transfer of the Li atom is very different from that of other atoms in the studied range of high pressures. The charge populations of the Li atom decrease with the pressure up to 60 GPa, then increase with the pressure.

Novel nonlinear wave transitions and interactions for(2+1)-dimensional generalized fifth-order Kd V equation

The(2 + 1)-dimensional generalized fifth-order Kd V(2GKd V) equation is revisited via combined physical and mathematical methods. By using the Hirota perturbation expansion technique and via setting the nonzero background wave on the multiple soliton solution of the2GKd V equation, breather waves are constructed, for which some transformed wave conditions are considered that yield abundant novel nonlinear waves including X/Y-Shaped(XS/YS),asymmetric M-Shaped(MS), W-Shaped(WS), Space-Curved(SC) and Oscillation M-Shaped(OMS) solitons. Furthermore, distinct nonlinear wave molecules and interactional structures involving the asymmetric MS, WS, XS/YS, SC solitons, and breathers, lumps are constructed after considering the corresponding existence conditions. The dynamical properties of the nonlinear molecular waves and interactional structures are revealed via analyzing the trajectory equations along with the change of the phase shifts.

Comparative Study on Two Melting Simulation Methods:Melting Curve of Gold

Melting simulation methods are of crucial importance to determining melting temperature of materials efficiently.A high-efficiency melting simulation method saves much simulation time and computational resources.To compare the efficiency of our newly developed shock melting(SM)method with that of the well-established two-phase(TP)method,we calculate the high-pressure melting curve of Au using the two methods based on the optimally selected interatomic potentials.Although we only use 640 atoms to determine the melting temperature of Au in the SM method,the resulting melting curve accords very well with the results from the TP method using much more atoms.Thus,this shows that a much smaller system size in SM method can still achieve a fully converged melting curve compared with the TP method,implying the robustness and efficiency of the SM method.