Three-dimensional wave packet dynamics

Manthe, U. and Koppel, H. (1991). Three-dimensional wave-packet dynamics on vibron-ically coupled dissociative potential energy surfaces, Chem. Phys. Lett. 178, 36-42. 

Manthe, U., Koppel, H., and Cederbaum, L.S. (1991). Dissociation and predissociation on coupled electronic potential energy surfaces A three-dimensional wave packet dynamical study, J. Chem. Phys. 95, 1709-1720. 

As already discussed, the approximate QD signal of a 120fs pulse exhibits two dominant vibrations which are caused by the Qs mode (310 to 320 fs) on the one hand, and by a slow pseudorot at ional mode (1 ps) on the other hand. Interestingly, the vibration along the Qs mode loses its pronounced character after 3ps (see Fig.3.51), i.e. the wave packet spreads out along this coordinate, as a movie of the three-dimensional wave packet dynamics of the B state shows [388]. This observation has already been interpreted as an effect of the anharmonicity of the PES and as intramolecular vibrational redistribution from dominantly Qs to g and (f vibration [62, 81]. The behavior described is also reflected by the approximate QD pump probe signal where the oscillation of period 310 to 320 fs caused by the Qs mode vanishes after a time of 4 to 5ps (see also Fig. 3.52). 

In a series of papers, Hirsch, Buenker, Petrongolo and collaborators have determined accurate three-dimensional diabatic potential-energy functions for the conically intersecting X Ai and A B2 states of NO2, see Refs. 145 and 146 and references therein. Santoro and Petrongolo have elaborated a detailed picture of the time-dependent wave-packet dynamics of this system initiated by ultrafast excitation of the A B state.The stationary absorption and emission spectra of NO2 are discussed in Chapter 16 (see also Chapter 7 and Refs. 7 and 99 for a brief discussion of the... 

These complementary experimental results can be explained to a great extent by quantum dynamical simulations of the real-time experiments. In Sect. 3.2.2, first the results obtained by means of two-dimensional (2d) ab initio potential-energy surfaces are briefly summarized. Even more sophisticated calculations are performed on three-dimensional (3d) ab initio potential-energy and transition dipole surfaces (Sect. 3.2.3). There, all three vibrational degrees of freedom of the Nas molecule are included in the theoretical treatment. The time-dependent wave packet dynamics elucidate the effect of ultrafast state preparation on the molecular dynamics. Extensive theoretical calculations indicate the possibility of initiating the molecular dynamics predominantly in selected modes during a certain time span by variation of the pump pulse duration (Sect. 3.2.4). 

For the bound Naa B system, 1.25 ps and 120 fs one-color real-time TPI spectroscopy, at moderate intensities, yielded preferential excitations of the relatively slow pseudorotation (3 ps) and the fast symmetric stretch mode (310 fs) respectively. Three-dimensional quantum chemical and quantum dynamical ab initio investigations fully corresponded to these experimental results. The time-dependent wave packet dynamics elucidate the effect of ultrafast state preparation on the molecular dynamics. Hence, these experiments manifest efficient control of molecular dynamics using the pulse duration as a control parameter. Since known cw spectra show the pseudorotation features only, this result demonstrates also that cw and femtosecond spectroscopy have complementary sensitivities for the excitation of different vibrational modes, thus neatly confirming the original conjecture of Zewail (see e.g. [425]). 

Gray S K and Balint-Kurti G G 1998 Quantum dynamics with real wave packets, including application to three-dimensional (J = 0)D + H2 HD + H reactive scattering J. Chem. Phys. 108 950... 

We now illustrate the utility of Eq. (27) in relating the RWP dynamics based on the arccosine mapping, Eq. (16), to the usual time-dependent Schrodinger equation dynamics, Eq. (1). We carried out three-dimensional (total angular momentum 7 = 0) wave packet calculations for the... 

Henriksen, N.E. and Heller, E.J. (1989). Quantum dynamics for vibrational and rotational degrees of freedom using Gaussian wave packets Application to the three-dimensional photodissociation dynamics of ICN, J. Chem. Phys. 91, 4700-4713. 

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