Diffusion Dynamics of Adsorbates from Tuneling and Other Quantum Effects

Physical and Analytical Chemistry Seminar

Lecturer: Prof. Roberto Marquardt

08 Nov 2015 @ 12:30

Location: Faculty Seminar Room

The formula proposed by van Hove in 1954 [1] for the dynamical structure factor (DSF) related to particle scattering at mobile adsorbates has recently been extended to the case when the adsobates’ excited states have finite lifetimes due to relaxation phenomena [2]. The new formula is evaluated quantum mechanically using wavefunctions, energies and lifetimes of vibrational states obtained for H/Pd(111) from first principle calculations. The results are capable of capturing qualitative features of diffusion rates measured for similar systems [3], if one assumes that the total rate obtained from the DSF is the sum of a diffusion and a friction rate.
In this talk, we present the new formula and show how applications perform on similar systems. In particular we show that quantum effects such as tunneling and resonances might be important for the diffusion of adsorbates even at room temperature.
[1] L. van Hove, Phys. Rev. 95, 249{262 (1954).
[2] T. Firmino, R. Marquardt, F. Gatti, W. Dong, J. Phys. Chem. Lett. 5 4270-4274 (2014).
[3] A. P. Jardine, G. Alexandrowicz, H. Hedgeland, W. Allison, J. Ellis, Phys. Chem. Chem. Phys. 11 3355-3374 (2009).