Abstract
Stochastic wave function formalism is briefly introduced and applied to study the dynamics of open quantum systems; in particular, the diffusion of Xe atoms adsorbed on a Pt(111) surface. By starting from a Lindblad functional and within the microscopic Caldeira–Leggett model for linear dissipation, a stochastic differential equation (Ito^-type differential equation) is straightforwardly obtained. The so-called intermediate scattering function within the ballistic regime is obtained, which is observable in Helium spin echo experiments. An ideal two-dimensional gas has been observed in this regime, leading to this function behaving as a Gaussian function. The influence of surface–adsorbate interaction is also analyzed by using the potential of two interactions describing flat and corrugated surfaces. Very low surface coverages are considered and, therefore, the adsorbate–adsorbate interaction is safely neglected. Good agreement is observed when our numerical results are compared with the corresponding experimental results and previous standard Langevin simulations.
Highlights
Most physical and chemical systems in nature are open classical or quantum systems.The corresponding dynamics are usually well described by considering an environment with an infinite number of degrees of freedom [1,2]
If the surface coverage θ is low, the adsorbates can be considered as independent particles, that is, the adsorbate–adsorbate interaction can be safely neglected
The Lindblad master equation, when it is solved by means of stochastic wave functions, provides a good physical description of the ballistic regime in this diffusion process
Summary
Most physical and chemical systems in nature are open classical or quantum systems. The corresponding dynamics are usually well described by considering an environment with an infinite number of degrees of freedom [1,2]. The diffusion of atoms/molecules on metal surfaces is usually considered in the quantum regime due to internal and/or external vibrations of adsorbates, as well as energy fluctuations at microscopic scale [7,8] These studies provide valuable information on adsorbate–substrate and adsorbate–adsorbate interactions. Among the different experimental techniques used to study these processes and extract information indirectly about interaction potentials, the so-called quasielastic He atom scattering (QHAS) [17,18,19,20] is considered as the surface science analogue of quasielastic neutron scattering, which is widely and successfully applied to analyze fast diffusion (time between jumps of the order of microseconds).
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