A new algorithm for modeling quantum dynamics of wave packets in a semiclassical limit was formulated and justified. The algorithm is valid in the case of two-particle systems and in the case of a single particle in any arbitrary central potential. The profile of the wave packet depending on the time for a single wave packet evolving in a one-dimensional (1D) Morse potential was obtained by direct computer simulations using the new algorithm. The results were compared with the calculation which was previously performed using the Initial Value Representation (IVR) method.
We study decoherence of the external degree of freedom of a tracer particle moving in a one-dimensional dilute Boltzmann gas. We find that phase averaging is the dominant decoherence effect, rather than information exchange between tracer and gas particles. While a coherent superposition of two wave packets with different mean positions quickly turns into a mixed state, it is demonstrated that such superpositions of different momenta are robust to phase averaging, until the two wave packets acquire a different position due to the different velocity of each wave packet.