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Hydrogen dissociation on Mg(0001) studied via quantum Monte Carlo calculations M. Pozzo1,2 and D. Alf1,2,3,4,*
 

Summary: Hydrogen dissociation on Mg(0001) studied via quantum Monte Carlo calculations
M. Pozzo1,2 and D. Alfè1,2,3,4,*
1Department of Earth Sciences, UCL, Gower Street, London WC1E 6BT, United Kingdom
2Materials Simulation Laboratory, UCL, Gower Street, London WC1E 6 BT, United Kingdom
3Department of Physics and Astronomy, UCL, Gower Street, London WC1E 6BT, United Kingdom
4London Centre for Nanotechnology, UCL, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
Received 23 August 2008; published 12 December 2008
We have used diffusion Monte Carlo DMC simulations to calculate the energy barrier for H2 dissociation
on the Mg 0001 surface. The calculations employ pseudopotentials and systematically improvable B-spline
basis sets to expand the single-particle orbitals used to construct the trial wave functions. Extensive tests on
system size, time step, and other sources of errors, performed on periodically repeated systems of up to 550
atoms, show that all these errors together can be reduced to 0.03 eV. The DMC dissociation barrier is
calculated to be 1.18 0.03 eV and is compared to those obtained with density-functional theory using various
exchange-correlation functionals, with values ranging between 0.44 and 1.07 eV.
DOI: 10.1103/PhysRevB.78.245313 PACS number s : 82.65. r, 71.10. w, 71.15. m
I. INTRODUCTION
The ability of calculating accurately the energetics of
metal hydrides is a key issue in the design of materials,
which might turn out to be useful in the current search for
suitable hydrogen storage HS media. In particular, the ki-

  

Source: Alfè, Dario - Departments of Earth Sciences & Physics and Astronomy, University College London

 

Collections: Physics; Geosciences