Dynamics of N₂ sticking on W(100): the decisive role of van der Waals interactions

Abstract

The reactive dynamics of N2 on W(100) has been investigated by means of quasi-classical trajectory calculations using an interpolated six-dimensional potential energy surface (PES) based on density functional theory energies obtained employing the vdW-DF2 functional. The dynamics are compared to those obtained using the PW91 functional and to experimental data. The results show that the new PES provides a significant improvement in the description of the reactivity in this system. We show that the long standing problem that constituted the large qualitative disagreement between the simulations performed with the PW91-PES and the experiments was due to the presence of energy barriers in the entrance channel that disappear when vdW forces are accounted for.

Computational approaches to dissociative chemisorption on metals: towards chemical accuracy

“…171,475 Though perhaps somewhat less accurate than the PIP-NN approach for diatomic molecules interacting with static metals, the CRP is often the method of choice for obtaining global PESs for diatomic molecules interacting with static metal surfaces. 132,156,476…”

“…The GLO method has been applied to e.g. sticking of H 2 to Pd surfaces, 475 vibrational excitation of H 2 scattering from Cu(111), 168 sticking of N 2 to W surfaces, 86,132 sticking of O 2 to Pd(100) 522 and Cu/Ru(0001), 130 and scattering of O 2 from Ag(111) 94 and Pt (111). 523 A more sophisticated treatment than the GLO is due to Jackson and co-workers, 524,525 and has been called various names, including e.g.…”

“…The QCT method is still very much used in studies of diatomic molecules scattering from reactive metal surfaces. Recent studies have addressed reaction of H 2 on Cu(111), 43,57,150,152,159,160,531,597 Cu(100), 150,172,597 Cu(211), 166,511 Ru(0001), 150,151 Ni(111), 476 Pd(111), 158,596,602 Pt(111), 150,156,163 Pt(211), 48 Au(111), 187 and Ag(111), 58,64,152,186 reaction of N 2 on Ru(0001), 59,138,139 on W(110), 86 and on W(100), 132,143 reaction of O 2 on Al(111), 35 Ag(111), 82 and Cu covered Ru(0001), 130 and reaction of HCl on Au (111). 85,133 Additionally, recent QCT studies have addressed vibrationally inelastic scattering of H 2 from Cu(111) 57 and of HCl from Au(111), 133 rotationally inelastic diffraction of H 2 from NiAl(110), 112 scattering of N 2 from W(110) 109 and from W(100),…”

“…In many, but not all cases good quantitative agreement was achieved 110 with experiments. 686 Crespos and co-workers 132 carried out QCT calculations on sticking of N 2 to W(100), using the GLO approach to incorporate surface atom motion and T s , and testing the PW91 312 and vdW2 327 DFs. While the measured S 0 were still overestimated substantially, far better agreement with experiment 687 was achieved employing the vdW2 than the PW91 DF (see Fig.…”

“…53,62,63 In the present state-of-the art in reaction dynamics, moleculemetal surface reactions are still often modeled with standard DFs at the generalized gradient approximation (GGA) level, like PBE, 21,51,53,58,62, its predecessor PW91, 53,61,65,78,86, and RPBE. 59,65,74,78,85,86,93,101,110,116,117,124,[130][131][132][133][134][135][136][137][138][139][140][141][142] However, GGAexchange DFs combined with correlation DFs approximately describing the attractive van der Waals interaction are increasingly used. 101,[143][144][145][146][147][148][149][150][151] Researchers are also starting to use meta-GGA (mGGA) DFs.…”