Item

Abstract

In summary, we have extended the EMT formalism derived for
fcc metals22 to the bcc case. We then fit the newly derived
formulae to DFT data for H interacting with W and Mo, which
led to full dimensional PESs and electron densities. We
employed the PESs and the electron densities to carry out
electronically non-adiabatic MD simulations of H atom scatter-
ing, following previous work that used the LDFA approximation
with a Langevin propagator. Specifically, we predict energy loss
distributions for H scattering from (111) and (110) facets of
these two metals at 2.76 eV incidence energy. Although no
experiments are currently available for bcc metals, our results
are similar to what has been seen for H scattering from fcc
metals. This suggests that the current results are likely to be a
reliable prediction of experiment. We find only subtle differ-
ences in the energy loss distributions arising from the scatter-
ing of H atom with these two metals; however, scattering from
the (111) and (110) facets are distinctly different. Remarkably,
on the (110) facet, we predict a clearly resolvable energy loss
peak that arises from sub-surface scattering. The calculations
Fig. 9 Distribution of specular scattering events as a function of the
energy loss and the depth of penetration of H atom scattered from (a)
Mo(110), (b) Mo(111), (c) W(110), and (d) W(111). The surface temperature is
70 K. The other conditions are the same as in Fig. 8. The signal above the
black, dashed line indicate from which layer the projectiles repelled. The
labels top, hcp and fcc refer to the high-symmetry sites of the (111) facet
and are shown in Fig. 1(b). The bin sizes are 0.027 eV and 0.063 Å.
Table 3 Sticking coefficient S0 computed from the same set of trajec-
tories that were used for the calculation of the specular energy loss
distributions shown in Fig. 8
System 300 K 70 K
H/Mo(110) 0.44 0.44
H/Mo(111) 0.40 0.41
H/W(110) 0.42 0.41
H/W(111) 0.40 0.40
Paper PCCPOpen Access Article. Published on 04 April 2022. Downloaded on 6/8/2022 3:06:58 PM.This article is licensed under aCreative Commons Attribution 3.0 Unported Licence.View Article Online
8746 | Phys. Chem. Chem. Phys., 2022, 24, 8738–8748 This journal is © the Owner Societies 2022predict that the subsurface scattering is most easily seen for H
scattering from W(110) at reduced surface temperatures.